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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 GPcRU8/h5H8vZ+W9ykGhdIq0TbnsKDuBABXH2GWcmfzl3IhXyIhNpUtMD8pALKpK
 BqCDHb5YPwhgvALfYfNUBw==

<SEC-DOCUMENT>0001140361-10-017799.txt : 20100428
<SEC-HEADER>0001140361-10-017799.hdr.sgml : 20100428
<ACCEPTANCE-DATETIME>20100428151059
ACCESSION NUMBER:		0001140361-10-017799
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100423
FILED AS OF DATE:		20100428
DATE AS OF CHANGE:		20100428

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Wynne John Bernard Jr
		CENTRAL INDEX KEY:			0001378241

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33710
		FILM NUMBER:		10776633

	MAIL ADDRESS:	
		STREET 1:		120 ALBANY STREET
		STREET 2:		TOWER II
		CITY:			NEW BRUNSWICK
		STATE:			NJ
		ZIP:			08901

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CLEAN DIESEL TECHNOLOGIES INC
		CENTRAL INDEX KEY:			0000949428
		STANDARD INDUSTRIAL CLASSIFICATION:	INDUSTRIAL INORGANIC CHEMICALS [2810]
		IRS NUMBER:				061393453
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		10 MIDDLE STREET
		STREET 2:		SUITE 1100
		CITY:			BRIDGEPORT
		STATE:			CT
		ZIP:			06604
		BUSINESS PHONE:		2034165290

	MAIL ADDRESS:	
		STREET 1:		10 MIDDLE STREET
		STREET 2:		SUITE 1100
		CITY:			BRIDGEPORT
		STATE:			CT
		ZIP:			06604
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 3
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0203</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2010-04-23</periodOfReport>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000949428</issuerCik>
        <issuerName>CLEAN DIESEL TECHNOLOGIES INC</issuerName>
        <issuerTradingSymbol>CDTI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001378241</rptOwnerCik>
            <rptOwnerName>Wynne John Bernard Jr</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O CLEAN DIESEL TECHNOLOGIES, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>10 MIDDLE ST., STE. 1100</rptOwnerStreet2>
            <rptOwnerCity>BRIDGEPORT</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06604</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>John Bernard Wynne Jr.</signatureName>
        <signatureDate>2010-04-28</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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