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| <?xml version="1.0" encoding="windows-1252"?> |
| <ownershipDocument> |
| <schemaVersion> X0306 </schemaVersion> |
| <documentType> 4 </documentType> |
| <periodOfReport> 2018-03-01 </periodOfReport> |
| <notSubjectToSection16> 0 </notSubjectToSection16> |
| <issuer> |
| | <issuerCik> 0000753772 </issuerCik> |
| | <issuerName> MEDIZONE INTERNATIONAL INC </issuerName> |
| | <issuerTradingSymbol> MZEI </issuerTradingSymbol> |
| | </issuer> |
| <reportingOwner> |
| | <reportingOwnerId> |
| | | <rptOwnerCik> 0001485899 </rptOwnerCik> |
| | | <rptOwnerName> Shannon Michael </rptOwnerName> |
| | | </reportingOwnerId> |
| | <reportingOwnerAddress> |
| | | <rptOwnerStreet1> 4 BRIDGE ST, UNIT #1 </rptOwnerStreet1> |
| | | <rptOwnerStreet2></rptOwnerStreet2> |
| | | <rptOwnerCity> PICTON </rptOwnerCity> |
| | | <rptOwnerState> A6 </rptOwnerState> |
| | | <rptOwnerZipCode> K0K 2T0 </rptOwnerZipCode> |
| | | <rptOwnerStateDescription> ONTARIO, CANADA </rptOwnerStateDescription> |
| | | </reportingOwnerAddress> |
| | <reportingOwnerRelationship> |
| | | <isDirector> 1 </isDirector> |
| | | <isOfficer> 1 </isOfficer> |
| | | <isTenPercentOwner> 0 </isTenPercentOwner> |
| | | <isOther> 0 </isOther> |
| | | <officerTitle> PRESIDENT </officerTitle> |
| | | <otherText></otherText> |
| | | </reportingOwnerRelationship> |
| | </reportingOwner> |
| <derivativeTable> |
| | <derivativeTransaction> |
| | | <securityTitle> |
| <value> Option to Purchase Common Stock </value> |
| </securityTitle> |
| | | <conversionOrExercisePrice> |
| <value> 0.13 </value> |
| </conversionOrExercisePrice> |
| | | <transactionDate> |
| <value> 2014-08-18 </value> |
| </transactionDate> |
| | | <deemedExecutionDate></deemedExecutionDate> |
| | | <transactionCoding> |
| <transactionFormType> 4 </transactionFormType> |
| <transactionCode> J </transactionCode> |
| <equitySwapInvolved> 0 </equitySwapInvolved> |
| <footnoteId id="F1"/> |
| </transactionCoding> |
| | | <transactionTimeliness></transactionTimeliness> |
| | | <transactionAmounts> |
| <transactionShares> |
| <value> 650000 </value> |
| </transactionShares> |
| <transactionPricePerShare> |
| <value> 0.13 </value> |
| </transactionPricePerShare> |
| <transactionAcquiredDisposedCode> |
| <value> D </value> |
| </transactionAcquiredDisposedCode> |
| </transactionAmounts> |
| | | <exerciseDate> |
| <value> 2014-08-18 </value> |
| </exerciseDate> |
| | | <expirationDate> |
| <value> 2019-08-15 </value> |
| </expirationDate> |
| | | <underlyingSecurity> |
| <underlyingSecurityTitle> |
| <value> Common Stock </value> |
| </underlyingSecurityTitle> |
| <underlyingSecurityShares> |
| <value> 650000 </value> |
| </underlyingSecurityShares> |
| </underlyingSecurity> |
| | | <postTransactionAmounts> |
| <sharesOwnedFollowingTransaction> |
| <value> 2500000 </value> |
| </sharesOwnedFollowingTransaction> |
| </postTransactionAmounts> |
| | | <ownershipNature> |
| <directOrIndirectOwnership> |
| <value> D </value> |
| </directOrIndirectOwnership> |
| </ownershipNature> |
| | | </derivativeTransaction> |
| | </derivativeTable> |
| <footnotes> |
| | <footnote id="F1"> Options were voluntarily surrendered by executive. </footnote> |
| | </footnotes> |
| <ownerSignature> |
| | <signatureName> /s/ Michael Shannon </signatureName> |
| | <signatureDate> 2018-03-02 </signatureDate> |
| | </ownerSignature> |
| </ownershipDocument> |
