-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 DU03cgcAe1FEmwSDZt6bTKh3xEnUr1erFSa7+992HZBsYaHWq//KDZnwQHqcPAj5
 AGdvnZOOfag5m3O4diYhKw==

<SEC-DOCUMENT>0001140361-07-021422.txt : 20071109
<SEC-HEADER>0001140361-07-021422.hdr.sgml : 20071109
<ACCEPTANCE-DATETIME>20071109111157
ACCESSION NUMBER:		0001140361-07-021422
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20071108
FILED AS OF DATE:		20071109
DATE AS OF CHANGE:		20071109

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			LYONDELL CHEMICAL CO
		CENTRAL INDEX KEY:			0000842635
		STANDARD INDUSTRIAL CLASSIFICATION:	INDUSTRIAL ORGANIC CHEMICALS [2860]
		IRS NUMBER:				954160558
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1221 MCKINNEY ST
		STREET 2:		SUITE 700
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77010
		BUSINESS PHONE:		713-652-7200

	MAIL ADDRESS:	
		STREET 1:		1221 MCKINNEY ST
		STREET 2:		SUITE 700
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77010

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	LYONDELL PETROCHEMICAL CO
		DATE OF NAME CHANGE:	19920703

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DENICOLA T KEVIN
		CENTRAL INDEX KEY:			0001220732

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-10145
		FILM NUMBER:		071229001

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		7136527280

	MAIL ADDRESS:	
		STREET 1:		1221 MCKINNEY ST.,
		STREET 2:		SUITE 700
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77010
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-11-08</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000842635</issuerCik>
        <issuerName>LYONDELL CHEMICAL CO</issuerName>
        <issuerTradingSymbol>LYO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001220732</rptOwnerCik>
            <rptOwnerName>DENICOLA T KEVIN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1221 MCKINNEY, SUITE 700</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77010</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior Vice President and CFO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2007-11-08</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value>E</value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>4175</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>57392</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5200</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By 401(K)</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ KERRY A. GALVIN as Attorney In Fact for T. Kevin DeNicola</signatureName>
        <signatureDate>2007-11-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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