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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,
 PAQXLEjDHNuZg9B9a0bEwl8LF/VFjrBf/QhNs5b//tvYQZVLjg/40IOXOER8eqGp
 DjLYbWpNGmqcSgAidEUdHQ==

<SEC-DOCUMENT>0001187907-03-000113.txt : 20030917
<SEC-HEADER>0001187907-03-000113.hdr.sgml : 20030917
<ACCEPTANCE-DATETIME>20030917113111
ACCESSION NUMBER:		0001187907-03-000113
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030917
FILED AS OF DATE:		20030917

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DUNLEAVY KAREN
		CENTRAL INDEX KEY:			0001187924

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-09279
		FILM NUMBER:		03898890

	BUSINESS ADDRESS:	
		STREET 1:		60 CUTTER MILL RD
		STREET 2:		STE 303
		CITY:			GREAT NECK
		STATE:			NY
		ZIP:			11021

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ONE LIBERTY PROPERTIES INC
		CENTRAL INDEX KEY:			0000712770
		STANDARD INDUSTRIAL CLASSIFICATION:	REAL ESTATE INVESTMENT TRUSTS [6798]
		IRS NUMBER:				133147497
		STATE OF INCORPORATION:			MD
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		60 CUTTER MILL RD
		STREET 2:		SUITE 303
		CITY:			GREAT NECK
		STATE:			NY
		ZIP:			11021-3190
		BUSINESS PHONE:		5164663100

	MAIL ADDRESS:	
		STREET 1:		60 CUTTER MILL ROAD
		STREET 2:		SUITE 303
		CITY:			GREAT NECK
		STATE:			NY
		ZIP:			11021-3190

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ONE LIBERTY FIRESTONE PROPERTIES INC
		DATE OF NAME CHANGE:	19851112
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-09-17</periodOfReport>
    <issuer>
        <issuerCik>0000712770</issuerCik>
        <issuerName>ONE LIBERTY PROPERTIES INC</issuerName>
        <issuerTradingSymbol>OLP</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001187924</rptOwnerCik>
            <rptOwnerName>DUNLEAVY KAREN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>60 CUTTER MILL ROAD</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 303</rptOwnerStreet2>
            <rptOwnerCity>GREAT NECK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>11021</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>Vice President, Financial</officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-09-17</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>2500</value></transactionShares><transactionPricePerShare><value>12.375</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>2900</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOf
Ownership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeHolding><securityTitle><value>Common Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>200</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>In IRA</value></natureOfOwnership></ownershipNature></nonDerivativeHolding><nonDerivativeHolding><securityTitle><value>Preferred Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>100</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>In IRA</value></natureOfOwnership></ownershipNature></nonDerivativeHolding></nonDerivativeTable><derivativeTable><derivativeTransaction><securityTitle><value>Employee Stock Option - Right to buy</value></se
curityTitle><conversionOrExercisePrice><value>12.375</value></conversionOrExercisePrice><transactionDate><value>2003-09-17</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>M</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>2500</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>1999-09-25</value></exerciseDate><expirationDate><value>2004-03-24</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>2500</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>0</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIn
directOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction><derivativeHolding><securityTitle><value>Employee Stock Option</value></securityTitle><conversionOrExercisePrice><value>11.125</value></conversionOrExercisePrice><exerciseDate><value>2000-09-23</value></exerciseDate><expirationDate><value>2005-03-22</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>3250</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>3250</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Employee Stock Option- Right to buy</value></securityTitle><
conversionOrExercisePrice><value>12.19</value></conversionOrExercisePrice><exerciseDate><value>2001-09-10</value></exerciseDate><expirationDate><value>2006-09-09</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>3500</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>3500</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding></derivativeTable><footnotes/><remarks/><ownerSignature><signatureName>Karen Dunleavy</signatureName><signatureDate>2003-09-17</signatureDate></ownerSignature></ownershipDocument>

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</SEC-DOCUMENT>
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