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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 K0OnVWNXnCqLE6sAGUQWNBT1Rqn3Ry1paYol9njahoxwCBsJcunRFXPGCoSwahEt
 23wNFwAxHdmrS45F4W1jIQ==

<SEC-DOCUMENT>0001140361-09-017260.txt : 20090730
<SEC-HEADER>0001140361-09-017260.hdr.sgml : 20090730
<ACCEPTANCE-DATETIME>20090730105330
ACCESSION NUMBER:		0001140361-09-017260
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090720
FILED AS OF DATE:		20090730
DATE AS OF CHANGE:		20090730

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			WESTLAKE CHEMICAL CORP
		CENTRAL INDEX KEY:			0001262823
		STANDARD INDUSTRIAL CLASSIFICATION:	INDUSTRIAL ORGANIC CHEMICALS [2860]
		IRS NUMBER:				760346924

	MAIL ADDRESS:	
		STREET 1:		2801 POST OAK BLVD
		STREET 2:		SUITE 600
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77056

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Chao James
		CENTRAL INDEX KEY:			0001299505

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-32260
		FILM NUMBER:		09972430

	MAIL ADDRESS:	
		STREET 1:		2801 POST OAK BLVD.
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77056
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-07-20</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001262823</issuerCik>
        <issuerName>WESTLAKE CHEMICAL CORP</issuerName>
        <issuerTradingSymbol>WLK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001299505</rptOwnerCik>
            <rptOwnerName>Chao James</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2801 POST OAK BLVD.</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77056</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chairman</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-07-20</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>5</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2400</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>94463</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>20000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Mother</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>103071</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Brother Albert Chao</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Even though reporting person and reporting person's mother share a household, reporting person disclaims beneficial ownership of these securities, and this report shall not be deemed an admission that the reporting person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose.</footnote>
        <footnote id="F2">Even though reporting person and reporting person's brother, Albert Chao, share a household, the reporting person disclaims beneficial ownership of these securities, and this report shall not be deemed an admission that the reporting person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose.</footnote>
    </footnotes>

    <remarks>46,005,277 shares are held through TTWF LP, a Delaware limited partnership.  Two trusts for the benefit of members of the Chao family, including the reporting person, are the managers of TTWFGP LLC, a Delaware limited liability company that is the general partner of TTWF LP.  The limited partners of TTWF LP are five trusts, principally for the benefit of members of the Chao family, including the reporting person, and two corporations owned, indirectly or directly, by certain of these trusts and by other entities owned by members of the Chao family, including the reporting person.  The reporting person shares investment and voting power with respect to the shares beneficially owned by TTWF LP.  The reporting person disclaims beneficial ownership of the shares except to the extent of his pecuniary interest therein.</remarks>

    <ownerSignature>
        <signatureName>James Chao by Julia Feng POA</signatureName>
        <signatureDate>2009-07-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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