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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,
 WbHCa3rQdDzVbQPWHfYk+6cIgAIGO60yk1zRFrS8saSxu8lXVG/C94SVdUE+RoK4
 ++vDzDy9aRsT6r9QqK/hOg==

<SEC-DOCUMENT>0001209191-03-025834.txt : 20031016
<SEC-HEADER>0001209191-03-025834.hdr.sgml : 20031016
<ACCEPTANCE-DATETIME>20031016161340
ACCESSION NUMBER:		0001209191-03-025834
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20031015
FILED AS OF DATE:		20031016

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			GENCORP INC
		CENTRAL INDEX KEY:			0000040888
		STANDARD INDUSTRIAL CLASSIFICATION:	FABRICATED RUBBER PRODUCTS, NEC [3060]
		IRS NUMBER:				340244000
		STATE OF INCORPORATION:			OH
		FISCAL YEAR END:			1130

	BUSINESS ADDRESS:	
		STREET 1:		HIGHWAY 50 & AEROJET ROAD
		CITY:			ANCHO CORDOVA
		STATE:			CA
		ZIP:			95670
		BUSINESS PHONE:		9163554000

	MAIL ADDRESS:	
		STREET 1:		HIGHWAY 50 & AEROJET ROAD
		CITY:			ANCHO CORDOVA
		STATE:			CA
		ZIP:			95670

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	GENERAL TIRE & RUBBER CO
		DATE OF NAME CHANGE:	19840330

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DIDION JAMES J
		CENTRAL INDEX KEY:			0001022081

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-01520
		FILM NUMBER:		03944004

	BUSINESS ADDRESS:	
		STREET 1:		533 S FREMONT AVE
		CITY:			LOS ANGELES
		STATE:			CA
		ZIP:			90071-1798
		BUSINESS PHONE:		2136133123

	MAIL ADDRESS:	
		STREET 1:		533 S FREMONT AVE
		CITY:			LOS ANGELES
		STATE:			CA
		ZIP:			90071-1798
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>FORM 4 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?><ownershipDocument><schemaVersion>X0201</schemaVersion>    <documentType>4</documentType><periodOfReport>2003-10-15</periodOfReport><notSubjectToSection16>0</notSubjectToSection16><issuer><issuerCik>0000040888</issuerCik><issuerName>GENCORP INC</issuerName>        <issuerTradingSymbol>GY</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId><rptOwnerCik>0001022081</rptOwnerCik><rptOwnerName>DIDION JAMES J</rptOwnerName></reportingOwnerId><reportingOwnerAddress><rptOwnerStreet1>HIGHWAY 50 &amp; AEROJET ROAD</rptOwnerStreet1><rptOwnerStreet2></rptOwnerStreet2><rptOwnerCity>RANCHO CORDOVA</rptOwnerCity><rptOwnerState>CA</rptOwnerState><rptOwnerZipCode>95670</rptOwnerZipCode><rptOwnerStateDescription></rptOwnerStateDescription></reportingOwnerAddress><reportingOwnerRelationship><isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><derivativeTable><derivativeTransaction><securityTi
tle><value>Phantom Stock Unit</value></securityTitle><conversionOrExercisePrice><footnoteId id="F1" /></conversionOrExercisePrice><transactionDate><value>2003-10-15</value></transactionDate><deemedExecutionDate></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F2" /></transactionCoding><transactionTimeliness><value></value></transactionTimeliness><transactionAmounts><transactionShares><value>1152.342</value></transactionShares><transactionPricePerShare><footnoteId id="F5" /></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><footnoteId id="F3" /></exerciseDate><expirationDate><footnoteId id="F4" /></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>1152.342</value></underlyingSecurityShares></un
derlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>10197</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>By Plan</value></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">Due to the nature of this transaction, the Conversion or Exercise Price of Derivative Security is not relevant to this transaction. </footnote><footnote id="F2">Phantom Stock Units acquired under the Deferred Compensation Plan for Nonemployee Directors on 10/15/03 including units acquired under the Dividend Reinvestment Plan on 8/29/03.</footnote><footnote id="F3">Due to the nature of this transaction, the Date Exercisable is not relevant to this transaction. </footnote><footnote id="F4">Due to the nature of this transaction, the Expiration Date is not relevant to this transaction. </footnote><footnote id="F5">Due to the nat
ure of this transaction, the Price of the Derivative Security is not relevant to this transaction.</footnote></footnotes><remarks></remarks><ownerSignature><signatureName>Gregory Kellam Scott as attorney-in-fact for James J. Didion</signatureName><signatureDate>2003-10-16</signatureDate></ownerSignature></ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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