<SEC-DOCUMENT>0001214659-20-009103.txt : 20201103
<SEC-HEADER>0001214659-20-009103.hdr.sgml : 20201103
<ACCEPTANCE-DATETIME>20201103090039
ACCESSION NUMBER:		0001214659-20-009103
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20201029
FILED AS OF DATE:		20201103
DATE AS OF CHANGE:		20201103

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Figueroa Richard
		CENTRAL INDEX KEY:			0001366217

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-09279
		FILM NUMBER:		201282049

	MAIL ADDRESS:	
		STREET 1:		60 CUTTER MILL ROAD
		STREET 2:		SUITE 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>marketforms-49902.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-10-29</periodOfReport>

    <issuer>
        <issuerCik>0000712770</issuerCik>
        <issuerName>ONE LIBERTY PROPERTIES INC</issuerName>
        <issuerTradingSymbol>OLP</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001366217</rptOwnerCik>
            <rptOwnerName>Figueroa Richard</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>false</isDirector>
            <isOfficer>true</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle>Sr. VP and Assistant Secretary</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-10-29</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>204</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>42364</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">On September 9, 2020, the issuer declared a quarterly dividend on its common stock of $.45 per share, payable on October 29, 2020 to stockholders of record on September 21, 2020. Stockholders were entitled to elect  whether the dividend payable to them would be paid in cash or shares of the issuer's  commons stock, provided that, with certain exceptions,  75% and 25% of the  aggregate dividend to be paid by the issuer would be paid in cash  and shares of common stock, respectively (the &quot;Limitation&quot;). The number of shares in column 4 represents the shares issued to the recipient after giving effect to the Limitation.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Richard Figueroa</signatureName>
        <signatureDate>2020-11-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
