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<FILING-DATE>20091008
<DATE-OF-FILING-DATE-CHANGE>20091008
<EFFECTIVENESS-DATE>20091008
<FILER>
<COMPANY-DATA>
<CONFORMED-NAME>CLEAN DIESEL TECHNOLOGIES INC
<CIK>0000949428
<ASSIGNED-SIC>2810
<IRS-NUMBER>061393453
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
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<FILM-NUMBER>091111339
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<STATE>CT
<ZIP>06604
<PHONE>2034165290
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            <street2>STE 1100</street2>
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            <stateOrCountry>CT</stateOrCountry>
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                <lastName>ASMUSSEN</lastName>
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                <city>FAIRFIELD</city>
                <stateOrCountry>CT</stateOrCountry>
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                <relationship>Director</relationship>
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                <middleName>ANTHONY</middleName>
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                <lastName>GRAY</lastName>
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                <street2>RICKMANSWORTH</street2>
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            <relatedPersonRelationshipList>
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            <industryGroupType>Business Services</industryGroupType>
        </industryGroup>
        <issuerSize>
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        <federalExemptionsExclusions>
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        <typeOfFiling>
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            </newOrAmendment>
            <dateOfFirstSale>
                <value>2009-10-01</value>
            </dateOfFirstSale>
        </typeOfFiling>
        <durationOfOffering>
            <moreThanOneYear>false</moreThanOneYear>
        </durationOfOffering>
        <typesOfSecuritiesOffered>
            <isEquityType>true</isEquityType>
        </typesOfSecuritiesOffered>
        <businessCombinationTransaction>
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        <minimumInvestmentAccepted>0</minimumInvestmentAccepted>
        <salesCompensationList></salesCompensationList>
        <offeringSalesAmounts>
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            <totalAmountSold>58879</totalAmountSold>
            <totalRemaining>0</totalRemaining>
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        <investors>
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            <signature>
                <issuerName>CLEAN DIESEL TECHNOLOGIES INC</issuerName>
                <signatureName>CW GRINNELL</signatureName>
                <nameOfSigner>CHARLES W GRINNELL</nameOfSigner>
                <signatureTitle>VICE PRESIDENT</signatureTitle>
                <signatureDate>2009-10-08</signatureDate>
            </signature>
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