| | | | | | | | | | | | | | | | | | | | | |
<?xml version="1.0" encoding="windows-1252"?> |
<!-- XBRL document created with Toppan Merrill Bridge 9.6.0.116 --> |
<!-- Based on XBRL 2.1 --> |
<!-- Created on: 5/15/2020 12:56:24 PM --> |
<!-- Modified on: 5/15/2020 12:56:24 PM --> |
<linkbase xmlns="http://www.xbrl.org/2003/linkbase" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"> |
| <roleRef xlink:type="simple" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-roles-2019-01-31.xsd#eedm" roleURI="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists"/> |
| <roleRef xlink:type="simple" xlink:href="hdsn-20200331.xsd#StatementConsolidatedBalanceSheetsParenthetical" roleURI="http://www.hudsontech.com/role/StatementConsolidatedBalanceSheetsParenthetical"/> |
| <roleRef xlink:type="simple" xlink:href="hdsn-20200331.xsd#StatementConsolidatedStatementsOfStockholdersEquity" roleURI="http://www.hudsontech.com/role/StatementConsolidatedStatementsOfStockholdersEquity"/> |
| <roleRef xlink:type="simple" xlink:href="hdsn-20200331.xsd#DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails" roleURI="http://www.hudsontech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails"/> |
| <roleRef xlink:type="simple" xlink:href="hdsn-20200331.xsd#DisclosurePropertyPlantAndEquipmentSummaryOfElementsOfPropertyPlantAndEquipmentDetails" roleURI="http://www.hudsontech.com/role/DisclosurePropertyPlantAndEquipmentSummaryOfElementsOfPropertyPlantAndEquipmentDetails"/> |
| <roleRef xlink:type="simple" xlink:href="hdsn-20200331.xsd#DisclosureLeasesBalanceSheetClassificationAndOtherInformationDetails" roleURI="http://www.hudsontech.com/role/DisclosureLeasesBalanceSheetClassificationAndOtherInformationDetails"/> |
| <roleRef xlink:type="simple" xlink:href="hdsn-20200331.xsd#DisclosureGoodwillAndIntangibleAssetsCompanySOtherIntangibleAssetsDetails" roleURI="http://www.hudsontech.com/role/DisclosureGoodwillAndIntangibleAssetsCompanySOtherIntangibleAssetsDetails"/> |
| <roleRef xlink:type="simple" xlink:href="hdsn-20200331.xsd#DisclosureShareBasedCompensationAdditionalInformationDetails" roleURI="http://www.hudsontech.com/role/DisclosureShareBasedCompensationAdditionalInformationDetails"/> |
| <roleRef xlink:type="simple" xlink:href="hdsn-20200331.xsd#DisclosureShortTermAndLongTermDebtAdditionalInformationDetails" roleURI="http://www.hudsontech.com/role/DisclosureShortTermAndLongTermDebtAdditionalInformationDetails"/> |
| <roleRef xlink:type="simple" xlink:href="hdsn-20200331.xsd#DisclosureRelatedPartyTransactionsDetails" roleURI="http://www.hudsontech.com/role/DisclosureRelatedPartyTransactionsDetails"/> |
| <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/> |
| <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/> |
| <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/> |
| <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/> |
| <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/> |
| <arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/notAll" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#notAll"/> |
| <definitionLink xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="extended" xlink:title="Extensible Enumeration Domain Members"/> |
| <definitionLink xlink:role="http://www.hudsontech.com/role/StatementConsolidatedBalanceSheetsParenthetical" xlink:type="extended" xlink:title="00105 - Statement - Consolidated Balance Sheets (Parenthetical)"> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="us-gaap_StatementClassOfStockAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementClassOfStockAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="us-gaap_ClassOfStockDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="us-gaap_ClassOfStockDomain_637251441828601519"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementClassOfStockAxis" xlink:to="us-gaap_ClassOfStockDomain_637251441828601519" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockMember" xlink:label="us-gaap_PreferredStockMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_PreferredStockMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SeriesAPreferredStockMember" xlink:label="us-gaap_SeriesAPreferredStockMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ClassOfStockDomain" xlink:to="us-gaap_SeriesAPreferredStockMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="us-gaap_PreferredStockParOrStatedValuePerShare"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockParOrStatedValuePerShare" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockLiquidationPreferenceValue" xlink:label="us-gaap_PreferredStockLiquidationPreferenceValue"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockLiquidationPreferenceValue" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="us-gaap_PreferredStockSharesAuthorized"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockSharesAuthorized" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="us-gaap_PreferredStockSharesIssued"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockSharesIssued" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="us-gaap_PreferredStockSharesOutstanding"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_PreferredStockSharesOutstanding" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockParOrStatedValuePerShare" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="us-gaap_CommonStockSharesAuthorized"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesAuthorized" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="us-gaap_CommonStockSharesIssued"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesIssued" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="us-gaap_CommonStockSharesOutstanding"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_CommonStockSharesOutstanding" priority="1" use="optional"/> |
| | </definitionLink> |
| <definitionLink xlink:role="http://www.hudsontech.com/role/StatementConsolidatedStatementsOfStockholdersEquity" xlink:type="extended" xlink:title="00300 - Statement - Consolidated Statements of Stockholders' Equity"> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="us-gaap_StatementEquityComponentsAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_StatementEquityComponentsAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="us-gaap_EquityComponentDomain_637251441828611523"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_StatementEquityComponentsAxis" xlink:to="us-gaap_EquityComponentDomain_637251441828611523" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockMember" xlink:label="us-gaap_CommonStockMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_CommonStockMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="us-gaap_AdditionalPaidInCapitalMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_AdditionalPaidInCapitalMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="us-gaap_RetainedEarningsMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_EquityComponentDomain" xlink:to="us-gaap_RetainedEarningsMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="us-gaap_StockholdersEquity"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StockholdersEquity" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="us-gaap_SharesOutstanding"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_SharesOutstanding" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProfitLoss" xlink:label="us-gaap_ProfitLoss"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_ProfitLoss" priority="1" use="optional"/> |
| | </definitionLink> |
| <definitionLink xlink:role="http://www.hudsontech.com/role/DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails" xlink:type="extended" xlink:title="40102 - Disclosure - Summary of Significant Accounting Policies - Additional Information (Details)"> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_SignificantAccountingPoliciesTable" xlink:label="hdsn_SignificantAccountingPoliciesTable"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnusualOrInfrequentItemAxis" xlink:label="us-gaap_UnusualOrInfrequentItemAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="hdsn_SignificantAccountingPoliciesTable" xlink:to="us-gaap_UnusualOrInfrequentItemAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnusualOrInfrequentItemDomain" xlink:label="us-gaap_UnusualOrInfrequentItemDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_UnusualOrInfrequentItemAxis" xlink:to="us-gaap_UnusualOrInfrequentItemDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnusualOrInfrequentItemDomain" xlink:label="us-gaap_UnusualOrInfrequentItemDomain_637251441828621523"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_UnusualOrInfrequentItemAxis" xlink:to="us-gaap_UnusualOrInfrequentItemDomain_637251441828621523" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_CoronavirusAidReliefAndEconomicSecurityActMember" xlink:label="hdsn_CoronavirusAidReliefAndEconomicSecurityActMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_UnusualOrInfrequentItemDomain" xlink:to="hdsn_CoronavirusAidReliefAndEconomicSecurityActMember" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="us-gaap_ConcentrationRiskByTypeAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="hdsn_SignificantAccountingPoliciesTable" xlink:to="us-gaap_ConcentrationRiskByTypeAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="us-gaap_ConcentrationRiskTypeDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_ConcentrationRiskByTypeAxis" xlink:to="us-gaap_ConcentrationRiskTypeDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="us-gaap_ConcentrationRiskTypeDomain_637251441828631512"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_ConcentrationRiskByTypeAxis" xlink:to="us-gaap_ConcentrationRiskTypeDomain_637251441828631512" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CustomerConcentrationRiskMember" xlink:label="us-gaap_CustomerConcentrationRiskMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ConcentrationRiskTypeDomain" xlink:to="us-gaap_CustomerConcentrationRiskMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="hdsn_SignificantAccountingPoliciesTable" xlink:to="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="us-gaap_TypeOfAdoptionMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="us-gaap_TypeOfAdoptionMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="us-gaap_TypeOfAdoptionMember_637251441828631512"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:to="us-gaap_TypeOfAdoptionMember_637251441828631512" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountingStandardsUpdate201609Member" xlink:label="us-gaap_AccountingStandardsUpdate201609Member"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_TypeOfAdoptionMember" xlink:to="us-gaap_AccountingStandardsUpdate201609Member" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MajorCustomersAxis" xlink:label="srt_MajorCustomersAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="hdsn_SignificantAccountingPoliciesTable" xlink:to="srt_MajorCustomersAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_NameOfMajorCustomerDomain" xlink:label="srt_NameOfMajorCustomerDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_MajorCustomersAxis" xlink:to="srt_NameOfMajorCustomerDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_NameOfMajorCustomerDomain" xlink:label="srt_NameOfMajorCustomerDomain_637251441828631512"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_MajorCustomersAxis" xlink:to="srt_NameOfMajorCustomerDomain_637251441828631512" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_OneCustomerMember" xlink:label="hdsn_OneCustomerMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_NameOfMajorCustomerDomain" xlink:to="hdsn_OneCustomerMember" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="us-gaap_ConcentrationRiskByBenchmarkAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="5" xlink:from="hdsn_SignificantAccountingPoliciesTable" xlink:to="us-gaap_ConcentrationRiskByBenchmarkAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:to="us-gaap_ConcentrationRiskBenchmarkDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="us-gaap_ConcentrationRiskBenchmarkDomain_637251441828641511"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:to="us-gaap_ConcentrationRiskBenchmarkDomain_637251441828641511" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueFromContractWithCustomerMember" xlink:label="us-gaap_RevenueFromContractWithCustomerMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ConcentrationRiskBenchmarkDomain" xlink:to="us-gaap_RevenueFromContractWithCustomerMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsReceivableMember" xlink:label="us-gaap_AccountsReceivableMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ConcentrationRiskBenchmarkDomain" xlink:to="us-gaap_AccountsReceivableMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="us-gaap_IncomeTaxAuthorityAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="6" xlink:from="hdsn_SignificantAccountingPoliciesTable" xlink:to="us-gaap_IncomeTaxAuthorityAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="us-gaap_IncomeTaxAuthorityDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_IncomeTaxAuthorityAxis" xlink:to="us-gaap_IncomeTaxAuthorityDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="us-gaap_IncomeTaxAuthorityDomain_637251441828641511"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_IncomeTaxAuthorityAxis" xlink:to="us-gaap_IncomeTaxAuthorityDomain_637251441828641511" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="us-gaap_StateAndLocalJurisdictionMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_IncomeTaxAuthorityDomain" xlink:to="us-gaap_StateAndLocalJurisdictionMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_ExpirationPeriodAxis" xlink:label="hdsn_ExpirationPeriodAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="7" xlink:from="hdsn_SignificantAccountingPoliciesTable" xlink:to="hdsn_ExpirationPeriodAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_ExpirationPeriodDomain" xlink:label="hdsn_ExpirationPeriodDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="hdsn_ExpirationPeriodAxis" xlink:to="hdsn_ExpirationPeriodDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_ExpirationPeriodDomain" xlink:label="hdsn_ExpirationPeriodDomain_637251441828651510"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="hdsn_ExpirationPeriodAxis" xlink:to="hdsn_ExpirationPeriodDomain_637251441828651510" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_NoExpirationMember" xlink:label="hdsn_NoExpirationMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="hdsn_ExpirationPeriodDomain" xlink:to="hdsn_NoExpirationMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_ExpirationThrough2023Member" xlink:label="hdsn_ExpirationThrough2023Member"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="hdsn_ExpirationPeriodDomain" xlink:to="hdsn_ExpirationThrough2023Member" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_SignificantAccountingPoliciesLineItems" xlink:label="hdsn_SignificantAccountingPoliciesLineItems"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="hdsn_SignificantAccountingPoliciesTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NumberOfReportableSegments" xlink:label="us-gaap_NumberOfReportableSegments"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="us-gaap_NumberOfReportableSegments" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsReceivableNet" xlink:label="us-gaap_AccountsReceivableNet"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="us-gaap_AccountsReceivableNet" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_ProductionAndImportationPermissionDescription" xlink:label="hdsn_ProductionAndImportationPermissionDescription"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="hdsn_ProductionAndImportationPermissionDescription" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="us-gaap_ConcentrationRiskPercentage1"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="us-gaap_ConcentrationRiskPercentage1" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_PercentageOfTaxableIncomeThatAreOffsetAgainstNetOperatingLossCarryoversAndCarryback" xlink:label="hdsn_PercentageOfTaxableIncomeThatAreOffsetAgainstNetOperatingLossCarryoversAndCarryback"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="hdsn_PercentageOfTaxableIncomeThatAreOffsetAgainstNetOperatingLossCarryoversAndCarryback" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_TaxCutsAndJobsActPreliminaryIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund" xlink:label="hdsn_TaxCutsAndJobsActPreliminaryIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="hdsn_TaxCutsAndJobsActPreliminaryIncomeTaxExpenseBenefitRelatedToAlternativeMinimumTaxRefund" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_PercentageOfAdjustedTaxableIncomeThroughModificationsToSections163J" xlink:label="hdsn_PercentageOfAdjustedTaxableIncomeThroughModificationsToSections163J"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="hdsn_PercentageOfAdjustedTaxableIncomeThroughModificationsToSections163J" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_IncreaseDecreaseInInterestExpenseThroughModificationsToSection163J" xlink:label="hdsn_IncreaseDecreaseInInterestExpenseThroughModificationsToSection163J"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="hdsn_IncreaseDecreaseInInterestExpenseThroughModificationsToSection163J" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLossCarryforwards" xlink:label="us-gaap_OperatingLossCarryforwards"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="us-gaap_OperatingLossCarryforwards" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_AnnualLimitationOfNol" xlink:label="hdsn_AnnualLimitationOfNol"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="hdsn_AnnualLimitationOfNol" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:label="us-gaap_DeferredTaxAssetsValuationAllowance"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="us-gaap_DeferredTaxAssetsValuationAllowance" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount" xlink:label="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="14" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillImpairmentLoss" xlink:label="us-gaap_GoodwillImpairmentLoss"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="15" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="us-gaap_GoodwillImpairmentLoss" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_CylinderDepositValue" xlink:label="hdsn_CylinderDepositValue"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="16" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="hdsn_CylinderDepositValue" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="us-gaap_OperatingLeaseRightOfUseAsset"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="17" xlink:from="hdsn_SignificantAccountingPoliciesLineItems" xlink:to="us-gaap_OperatingLeaseRightOfUseAsset" priority="1" use="optional"/> |
| | </definitionLink> |
| <definitionLink xlink:role="http://www.hudsontech.com/role/DisclosurePropertyPlantAndEquipmentSummaryOfElementsOfPropertyPlantAndEquipmentDetails" xlink:type="extended" xlink:title="40401 - Disclosure - Property, plant and equipment - Summary of Elements of property, plant and equipment (Details)"> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="us-gaap_PropertyPlantAndEquipmentByTypeAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="us-gaap_PropertyPlantAndEquipmentByTypeAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="us-gaap_PropertyPlantAndEquipmentTypeDomain_637251441828701520"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:to="us-gaap_PropertyPlantAndEquipmentTypeDomain_637251441828701520" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LandMember" xlink:label="us-gaap_LandMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_LandMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LandImprovementsMember" xlink:label="us-gaap_LandImprovementsMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_LandImprovementsMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BuildingMember" xlink:label="us-gaap_BuildingMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_BuildingMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BuildingImprovementsMember" xlink:label="us-gaap_BuildingImprovementsMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_BuildingImprovementsMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_CylindersMember" xlink:label="hdsn_CylindersMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="hdsn_CylindersMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquipmentMember" xlink:label="us-gaap_EquipmentMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_EquipmentMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsHeldUnderCapitalLeasesMember" xlink:label="us-gaap_AssetsHeldUnderCapitalLeasesMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_AssetsHeldUnderCapitalLeasesMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_VehiclesMember" xlink:label="us-gaap_VehiclesMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_VehiclesMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ComputerEquipmentMember" xlink:label="us-gaap_ComputerEquipmentMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_ComputerEquipmentMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FurnitureAndFixturesMember" xlink:label="us-gaap_FurnitureAndFixturesMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_FurnitureAndFixturesMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LeaseholdImprovementsMember" xlink:label="us-gaap_LeaseholdImprovementsMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_LeaseholdImprovementsMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetUnderConstructionMember" xlink:label="us-gaap_AssetUnderConstructionMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:to="us-gaap_AssetUnderConstructionMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:to="srt_RangeAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="srt_RangeMember_637251441828711519"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember_637251441828711519" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="us-gaap_PropertyPlantAndEquipmentLineItems"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="us-gaap_PropertyPlantAndEquipmentGross"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentGross" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="us-gaap_PropertyPlantAndEquipmentNet"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentNet" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="us-gaap_PropertyPlantAndEquipmentUsefulLife"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_PropertyPlantAndEquipmentLineItems" xlink:to="us-gaap_PropertyPlantAndEquipmentUsefulLife" priority="1" use="optional"/> |
| | </definitionLink> |
| <definitionLink xlink:role="http://www.hudsontech.com/role/DisclosureLeasesBalanceSheetClassificationAndOtherInformationDetails" xlink:type="extended" xlink:title="40502 - Disclosure - Leases - Balance Sheet Classification and Other Information (Details)"> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="us-gaap_BalanceSheetLocationAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_BalanceSheetLocationAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="us-gaap_BalanceSheetLocationDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_BalanceSheetLocationAxis" xlink:to="us-gaap_BalanceSheetLocationDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="us-gaap_BalanceSheetLocationDomain_637251441828721512"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_BalanceSheetLocationAxis" xlink:to="us-gaap_BalanceSheetLocationDomain_637251441828721512" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesMember" xlink:label="us-gaap_AccountsPayableAndAccruedLiabilitiesMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_BalanceSheetLocationDomain" xlink:to="us-gaap_AccountsPayableAndAccruedLiabilitiesMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_BalanceSheetClassificationAbstract" xlink:label="hdsn_BalanceSheetClassificationAbstract"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_BalanceSheetClassificationAbstract" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent" xlink:label="us-gaap_OperatingLeaseLiabilityCurrent"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="hdsn_BalanceSheetClassificationAbstract" xlink:to="us-gaap_OperatingLeaseLiabilityCurrent" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:label="us-gaap_OperatingLeaseLiabilityNoncurrent"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="hdsn_BalanceSheetClassificationAbstract" xlink:to="us-gaap_OperatingLeaseLiabilityNoncurrent" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseLiability" xlink:label="us-gaap_OperatingLeaseLiability"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="hdsn_BalanceSheetClassificationAbstract" xlink:to="us-gaap_OperatingLeaseLiability" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_OtherInformationAbstract" xlink:label="hdsn_OtherInformationAbstract"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_OtherInformationAbstract" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:label="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="hdsn_OtherInformationAbstract" xlink:to="us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" xlink:label="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="hdsn_OtherInformationAbstract" xlink:to="us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent" priority="1" use="optional"/> |
| | </definitionLink> |
| <definitionLink xlink:role="http://www.hudsontech.com/role/DisclosureGoodwillAndIntangibleAssetsCompanySOtherIntangibleAssetsDetails" xlink:type="extended" xlink:title="40601 - Disclosure - Goodwill and intangible assets - Company's other intangible assets (Details)"> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_637251441828731515"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_637251441828731515" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PatentsMember" xlink:label="us-gaap_PatentsMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="us-gaap_PatentsMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NoncompeteAgreementsMember" xlink:label="us-gaap_NoncompeteAgreementsMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="us-gaap_NoncompeteAgreementsMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="us-gaap_CustomerRelationshipsMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="us-gaap_CustomerRelationshipsMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AboveMarketLeasesMember" xlink:label="us-gaap_AboveMarketLeasesMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="us-gaap_AboveMarketLeasesMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="srt_RangeAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="us-gaap_FiniteLivedIntangibleAssetsLineItems"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1" xlink:label="us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="us-gaap_FiniteLivedIntangibleAssetsGross"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_FiniteLivedIntangibleAssetsGross" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="us-gaap_FiniteLivedIntangibleAssetsNet"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:to="us-gaap_FiniteLivedIntangibleAssetsNet" priority="1" use="optional"/> |
| | </definitionLink> |
| <definitionLink xlink:role="http://www.hudsontech.com/role/DisclosureShareBasedCompensationAdditionalInformationDetails" xlink:type="extended" xlink:title="40703 - Disclosure - Share-based compensation - Additional Information (Details)"> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:label="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="us-gaap_PlanNameAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:to="us-gaap_PlanNameAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="us-gaap_PlanNameDomain_637251441828751510"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameDomain_637251441828751510" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_TwoThousandAndFourteenStockIncentivePlanMember" xlink:label="hdsn_TwoThousandAndFourteenStockIncentivePlanMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_PlanNameDomain" xlink:to="hdsn_TwoThousandAndFourteenStockIncentivePlanMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_TwoThousandAndEighteenStockIncentivePlanMember" xlink:label="hdsn_TwoThousandAndEighteenStockIncentivePlanMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_PlanNameDomain" xlink:to="hdsn_TwoThousandAndEighteenStockIncentivePlanMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:to="srt_RangeAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="us-gaap_AllocatedShareBasedCompensationExpense"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="us-gaap_AllocatedShareBasedCompensationExpense" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageFromFairMarketPrice" xlink:label="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageFromFairMarketPrice"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="hdsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageFromFairMarketPrice" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsAggregateIntrinsicValueNonvested" xlink:label="hdsn_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsAggregateIntrinsicValueNonvested"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="hdsn_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsAggregateIntrinsicValueNonvested" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" priority="1" use="optional"/> |
| | </definitionLink> |
| <definitionLink xlink:role="http://www.hudsontech.com/role/DisclosureShortTermAndLongTermDebtAdditionalInformationDetails" xlink:type="extended" xlink:title="40803 - Disclosure - Short-term and long-term debt - Additional Information (Details)"> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="us-gaap_StatementTable"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="us-gaap_TypeOfArrangementAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_TypeOfArrangementAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_TypeOfArrangementAxis" xlink:to="us-gaap_ArrangementsAndNonarrangementTransactionsMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="us-gaap_ArrangementsAndNonarrangementTransactionsMember_637251441828771512"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_TypeOfArrangementAxis" xlink:to="us-gaap_ArrangementsAndNonarrangementTransactionsMember_637251441828771512" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_RevolverGuarantyAndSecurityAgreementMember" xlink:label="hdsn_RevolverGuarantyAndSecurityAgreementMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:to="hdsn_RevolverGuarantyAndSecurityAgreementMember" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityAxis" xlink:label="us-gaap_LineOfCreditFacilityAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="2" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_LineOfCreditFacilityAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="us-gaap_LineOfCreditFacilityLenderDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_LineOfCreditFacilityAxis" xlink:to="us-gaap_LineOfCreditFacilityLenderDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityLenderDomain" xlink:label="us-gaap_LineOfCreditFacilityLenderDomain_637251441828771512"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_LineOfCreditFacilityAxis" xlink:to="us-gaap_LineOfCreditFacilityLenderDomain_637251441828771512" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_VehicleAndEquipmentLoansMember" xlink:label="hdsn_VehicleAndEquipmentLoansMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_LineOfCreditFacilityLenderDomain" xlink:to="hdsn_VehicleAndEquipmentLoansMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_TermLoanMember" xlink:label="hdsn_TermLoanMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_LineOfCreditFacilityLenderDomain" xlink:to="hdsn_TermLoanMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_PncBankMember" xlink:label="hdsn_PncBankMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_LineOfCreditFacilityLenderDomain" xlink:to="hdsn_PncBankMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_DomesticRateLoansMember" xlink:label="hdsn_DomesticRateLoansMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="hdsn_PncBankMember" xlink:to="hdsn_DomesticRateLoansMember" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_EurodollarRateLoansMember" xlink:label="hdsn_EurodollarRateLoansMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="hdsn_PncBankMember" xlink:to="hdsn_EurodollarRateLoansMember" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_WellsFargoMember" xlink:label="hdsn_WellsFargoMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_LineOfCreditFacilityLenderDomain" xlink:to="hdsn_WellsFargoMember" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="us-gaap_SubsequentEventTypeAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="3" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_SubsequentEventTypeAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="us-gaap_SubsequentEventTypeDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="us-gaap_SubsequentEventTypeDomain_637251441828781512"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeDomain_637251441828781512" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="us-gaap_SubsequentEventMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_SubsequentEventTypeDomain" xlink:to="us-gaap_SubsequentEventMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:label="srt_RangeAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="4" xlink:from="us-gaap_StatementTable" xlink:to="srt_RangeAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="srt_RangeMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_RangeAxis" xlink:to="srt_RangeMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MinimumMember" xlink:label="srt_MinimumMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_RangeMember" xlink:to="srt_MinimumMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MaximumMember" xlink:label="srt_MaximumMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_RangeMember" xlink:to="srt_MaximumMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="us-gaap_CreditFacilityAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="5" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_CreditFacilityAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="us-gaap_CreditFacilityDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_CreditFacilityAxis" xlink:to="us-gaap_CreditFacilityDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="us-gaap_CreditFacilityDomain_637251441828791514"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_CreditFacilityAxis" xlink:to="us-gaap_CreditFacilityDomain_637251441828791514" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_AmendedAndRestatedRevolvingCreditAndSecurityAgreementMember" xlink:label="hdsn_AmendedAndRestatedRevolvingCreditAndSecurityAgreementMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="hdsn_AmendedAndRestatedRevolvingCreditAndSecurityAgreementMember" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_SwingLineLoanMember" xlink:label="hdsn_SwingLineLoanMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="hdsn_AmendedAndRestatedRevolvingCreditAndSecurityAgreementMember" xlink:to="hdsn_SwingLineLoanMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LetterOfCreditMember" xlink:label="us-gaap_LetterOfCreditMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="hdsn_AmendedAndRestatedRevolvingCreditAndSecurityAgreementMember" xlink:to="us-gaap_LetterOfCreditMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_TermLoanFacilityMember" xlink:label="hdsn_TermLoanFacilityMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="hdsn_TermLoanFacilityMember" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_WaiverAndFirstAmendmentToTermLoanCreditAndSecurityAgreementMember" xlink:label="hdsn_WaiverAndFirstAmendmentToTermLoanCreditAndSecurityAgreementMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="hdsn_WaiverAndFirstAmendmentToTermLoanCreditAndSecurityAgreementMember" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_WaiverAndSecondAmendmentToTermLoanCreditAndSecurityAgreementMember" xlink:label="hdsn_WaiverAndSecondAmendmentToTermLoanCreditAndSecurityAgreementMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="hdsn_WaiverAndSecondAmendmentToTermLoanCreditAndSecurityAgreementMember" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_FourthAmendmentMember" xlink:label="hdsn_FourthAmendmentMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="hdsn_FourthAmendmentMember" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_FifthAmendmentToTermLoanCreditAndSecurityAgreementMember" xlink:label="hdsn_FifthAmendmentToTermLoanCreditAndSecurityAgreementMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="hdsn_FifthAmendmentToTermLoanCreditAndSecurityAgreementMember" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="us-gaap_RevolvingCreditFacilityMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_CreditFacilityDomain" xlink:to="us-gaap_RevolvingCreditFacilityMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="us-gaap_VariableRateAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="6" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_VariableRateAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="us-gaap_VariableRateDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_VariableRateAxis" xlink:to="us-gaap_VariableRateDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="us-gaap_VariableRateDomain_637251441828811516"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_VariableRateAxis" xlink:to="us-gaap_VariableRateDomain_637251441828811516" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_LondonInterbankOfferedRateDailyLiborMember" xlink:label="hdsn_LondonInterbankOfferedRateDailyLiborMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_VariableRateDomain" xlink:to="hdsn_LondonInterbankOfferedRateDailyLiborMember" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FederalFundsPurchasedMember" xlink:label="us-gaap_FederalFundsPurchasedMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_VariableRateDomain" xlink:to="us-gaap_FederalFundsPurchasedMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EurodollarMember" xlink:label="us-gaap_EurodollarMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_VariableRateDomain" xlink:to="us-gaap_EurodollarMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShortTermDebtTypeAxis" xlink:label="us-gaap_ShortTermDebtTypeAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="7" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_ShortTermDebtTypeAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="us-gaap_ShortTermDebtTypeDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_ShortTermDebtTypeAxis" xlink:to="us-gaap_ShortTermDebtTypeDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="us-gaap_ShortTermDebtTypeDomain_637251441828821517"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_ShortTermDebtTypeAxis" xlink:to="us-gaap_ShortTermDebtTypeDomain_637251441828821517" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_PncFacilityMember" xlink:label="hdsn_PncFacilityMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_ShortTermDebtTypeDomain" xlink:to="hdsn_PncFacilityMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_FCCRMember" xlink:label="hdsn_FCCRMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_ShortTermDebtTypeDomain" xlink:to="hdsn_FCCRMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_TLRMember" xlink:label="hdsn_TLRMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_ShortTermDebtTypeDomain" xlink:to="hdsn_TLRMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="us-gaap_LongtermDebtTypeAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="8" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_LongtermDebtTypeAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="us-gaap_LongtermDebtTypeDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="us-gaap_LongtermDebtTypeDomain_637251441828831516"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_LongtermDebtTypeAxis" xlink:to="us-gaap_LongtermDebtTypeDomain_637251441828831516" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_PaycheckProtectionProgramMember" xlink:label="hdsn_PaycheckProtectionProgramMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_LongtermDebtTypeDomain" xlink:to="hdsn_PaycheckProtectionProgramMember" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="us-gaap_DebtInstrumentAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="9" xlink:from="us-gaap_StatementTable" xlink:to="us-gaap_DebtInstrumentAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="us-gaap_DebtInstrumentNameDomain_637251441828841512"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="us-gaap_DebtInstrumentAxis" xlink:to="us-gaap_DebtInstrumentNameDomain_637251441828841512" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_CaresActLoanMember" xlink:label="hdsn_CaresActLoanMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="us-gaap_DebtInstrumentNameDomain" xlink:to="hdsn_CaresActLoanMember" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_StatementScenarioAxis" xlink:label="srt_StatementScenarioAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="10" xlink:from="us-gaap_StatementTable" xlink:to="srt_StatementScenarioAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ScenarioUnspecifiedDomain" xlink:label="srt_ScenarioUnspecifiedDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_StatementScenarioAxis" xlink:to="srt_ScenarioUnspecifiedDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ScenarioUnspecifiedDomain" xlink:label="srt_ScenarioUnspecifiedDomain_637251441828841512"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_StatementScenarioAxis" xlink:to="srt_ScenarioUnspecifiedDomain_637251441828841512" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_EffectiveMarch312020Member" xlink:label="hdsn_EffectiveMarch312020Member"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_ScenarioUnspecifiedDomain" xlink:to="hdsn_EffectiveMarch312020Member" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_EffectiveDecember312020Member" xlink:label="hdsn_EffectiveDecember312020Member"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="srt_ScenarioUnspecifiedDomain" xlink:to="hdsn_EffectiveDecember312020Member" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_ThroughMarch312020Member" xlink:label="hdsn_ThroughMarch312020Member"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="srt_ScenarioUnspecifiedDomain" xlink:to="hdsn_ThroughMarch312020Member" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_FromApril12020ThroughMarch312021Member" xlink:label="hdsn_FromApril12020ThroughMarch312021Member"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="srt_ScenarioUnspecifiedDomain" xlink:to="hdsn_FromApril12020ThroughMarch312021Member" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_FromApril12021AndThereafterMember" xlink:label="hdsn_FromApril12021AndThereafterMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="srt_ScenarioUnspecifiedDomain" xlink:to="hdsn_FromApril12021AndThereafterMember" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="us-gaap_StatementLineItems"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_StatementTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_DebtInstrumentAdditionalPercentagePointsInterest" xlink:label="hdsn_DebtInstrumentAdditionalPercentagePointsInterest"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_DebtInstrumentAdditionalPercentagePointsInterest" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_RightToDominionInEventOfDefaultOrUndrawnAvailability" xlink:label="hdsn_RightToDominionInEventOfDefaultOrUndrawnAvailability"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_RightToDominionInEventOfDefaultOrUndrawnAvailability" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidityToBeDerivedFromAvailability" xlink:label="hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidityToBeDerivedFromAvailability"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="6" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_LineOfCreditFacilityCovenantComplianceMinimumLiquidityToBeDerivedFromAvailability" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_MinimumAggregateUndrawnLoanAvailability" xlink:label="hdsn_MinimumAggregateUndrawnLoanAvailability"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="7" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_MinimumAggregateUndrawnLoanAvailability" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_FixedChargesCoverageRatio" xlink:label="hdsn_FixedChargesCoverageRatio"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="8" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_FixedChargesCoverageRatio" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_PeriodForFixedChargeCoverageRatio" xlink:label="hdsn_PeriodForFixedChargeCoverageRatio"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="9" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_PeriodForFixedChargeCoverageRatio" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RepaymentsOfLinesOfCredit" xlink:label="us-gaap_RepaymentsOfLinesOfCredit"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="10" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_RepaymentsOfLinesOfCredit" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="us-gaap_DebtInstrumentFaceAmount"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="11" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DebtInstrumentFaceAmount" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_DebtInstrumentLineOfCreditFacilityPeriodicPaymentPrincipal" xlink:label="hdsn_DebtInstrumentLineOfCreditFacilityPeriodicPaymentPrincipal"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="12" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_DebtInstrumentLineOfCreditFacilityPeriodicPaymentPrincipal" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="13" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DebtInstrumentInterestRateStatedPercentage" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_TotalLeverageRatio" xlink:label="hdsn_TotalLeverageRatio"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="14" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_TotalLeverageRatio" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_MinimumAggregateUndrawnAvailabilityExcessCashFlowCalculation" xlink:label="hdsn_MinimumAggregateUndrawnAvailabilityExcessCashFlowCalculation"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="15" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_MinimumAggregateUndrawnAvailabilityExcessCashFlowCalculation" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_DebtInstrumentLastTwelveMonthsAdjustedEarningsBeforeInterestTaxDepreciationAndAmortization" xlink:label="hdsn_DebtInstrumentLastTwelveMonthsAdjustedEarningsBeforeInterestTaxDepreciationAndAmortization"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="16" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_DebtInstrumentLastTwelveMonthsAdjustedEarningsBeforeInterestTaxDepreciationAndAmortization" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_DebtInstrumentAmendmentFeePercent" xlink:label="hdsn_DebtInstrumentAmendmentFeePercent"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="17" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_DebtInstrumentAmendmentFeePercent" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallCommenceTransaction" xlink:label="hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallCommenceTransaction"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="18" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallCommenceTransaction" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallConsummateTransaction" xlink:label="hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallConsummateTransaction"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="19" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_DebtInstrumentThresholdPeriodAfterTriggerEventEntityShallConsummateTransaction" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_DeferredFinancingCosts" xlink:label="hdsn_DeferredFinancingCosts"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="20" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_DeferredFinancingCosts" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnsecuredDebt" xlink:label="us-gaap_UnsecuredDebt"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="21" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_UnsecuredDebt" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentTerm" xlink:label="us-gaap_DebtInstrumentTerm"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="22" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_DebtInstrumentTerm" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongTermDebtTerm" xlink:label="us-gaap_LongTermDebtTerm"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="23" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LongTermDebtTerm" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_DebtInstrumentInterestDeferralTerm" xlink:label="hdsn_DebtInstrumentInterestDeferralTerm"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="24" xlink:from="us-gaap_StatementLineItems" xlink:to="hdsn_DebtInstrumentInterestDeferralTerm" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityExpirationPeriod" xlink:label="us-gaap_LineOfCreditFacilityExpirationPeriod"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="25" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LineOfCreditFacilityExpirationPeriod" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityInterestRateDescription" xlink:label="us-gaap_LineOfCreditFacilityInterestRateDescription"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="26" xlink:from="us-gaap_StatementLineItems" xlink:to="us-gaap_LineOfCreditFacilityInterestRateDescription" priority="1" use="optional"/> |
| | </definitionLink> |
| <definitionLink xlink:role="http://www.hudsontech.com/role/DisclosureRelatedPartyTransactionsDetails" xlink:type="extended" xlink:title="40901 - Disclosure - Related Party Transactions (Details)"> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:label="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_TitleOfIndividualAxis" xlink:label="srt_TitleOfIndividualAxis"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" order="1" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="srt_TitleOfIndividualAxis" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" order="1" xlink:from="srt_TitleOfIndividualAxis" xlink:to="srt_TitleOfIndividualWithRelationshipToEntityDomain" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="srt_TitleOfIndividualWithRelationshipToEntityDomain_637251441828931525"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" order="1" xlink:from="srt_TitleOfIndividualAxis" xlink:to="srt_TitleOfIndividualWithRelationshipToEntityDomain_637251441828931525" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_VicePresidentMember" xlink:label="srt_VicePresidentMember"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="1" xlink:from="srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="srt_VicePresidentMember" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyTransactionLineItems" xlink:label="us-gaap_RelatedPartyTransactionLineItems"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" order="1" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" use="optional" xbrldt:contextElement="segment" xbrldt:closed="true"/> |
| | <loc xlink:type="locator" xlink:href="hdsn-20200331.xsd#hdsn_MonthlyConsultingFee" xlink:label="hdsn_MonthlyConsultingFee"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="2" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="hdsn_MonthlyConsultingFee" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="3" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="4" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DeferredCompensationArrangementWithIndividualSharesIssued" priority="1" use="optional"/> |
| | <loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualExercisePrice" xlink:label="us-gaap_DeferredCompensationArrangementWithIndividualExercisePrice"/> |
| | <definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" order="5" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_DeferredCompensationArrangementWithIndividualExercisePrice" priority="1" use="optional"/> |
| | </definitionLink> |
| </linkbase> |