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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 QDZsidSYz1vf8Z1BB9kvASjIjKLNsnw2M0vkF7Th4a7A4d04kFgscbbzSKAhRl7U
 8oZ51OvBxkk9ORnnUfA3vg==

<SEC-DOCUMENT>0001182489-08-000546.txt : 20080527
<SEC-HEADER>0001182489-08-000546.hdr.sgml : 20080526
<ACCEPTANCE-DATETIME>20080527140529
ACCESSION NUMBER:		0001182489-08-000546
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080524
FILED AS OF DATE:		20080527
DATE AS OF CHANGE:		20080527

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			GENTEK INC
		CENTRAL INDEX KEY:			0001077552
		STANDARD INDUSTRIAL CLASSIFICATION:	CHEMICALS & ALLIED PRODUCTS [2800]
		IRS NUMBER:				020505547
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		C/O GENTEK INC
		STREET 2:		90 EAST HALSEY ROAD
		CITY:			PARSIPPANY
		STATE:			NJ
		ZIP:			07054
		BUSINESS PHONE:		9738846952

	MAIL ADDRESS:	
		STREET 1:		C/O GENTEK INC
		STREET 2:		90 EAST HALSEY ROAD
		CITY:			PARSIPPANY
		STATE:			NJ
		ZIP:			07054

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Testa Thomas
		CENTRAL INDEX KEY:			0001324128

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-14789
		FILM NUMBER:		08860263

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		973-515-0900

	MAIL ADDRESS:	
		STREET 1:		90 EAST HALSEY ROAD
		CITY:			PARSIPPANY
		STATE:			NJ
		ZIP:			07054
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-05-24</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001077552</issuerCik>
        <issuerName>GENTEK INC</issuerName>
        <issuerTradingSymbol>GETI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001324128</rptOwnerCik>
            <rptOwnerName>Testa Thomas</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O 90 EAST HALSEY ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>PARSIPPANY</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>07054</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP &amp; Chief Financial Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-05-24</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>428</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>28.98</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>32371</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents shares surrendered to the Company pursuant to Rule 16b-3(e) in satisfaction of the reporting person's tax liability in connection with the vesting of restricted stock, the grant of which has been previously reported.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>James Imbriaco, by Power of Attorney</signatureName>
        <signatureDate>2008-05-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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