<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0607</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2026-04-20</periodOfReport>

    <noSecuritiesOwned>1</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000110621</issuerCik>
        <issuerName>RPM INTERNATIONAL INC/DE/</issuerName>
        <issuerTradingSymbol>RPM</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001643493</rptOwnerCik>
            <rptOwnerName>Gentile Tom</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>C/O RPM INTERNATIONAL INC.</rptOwnerStreet1>
            <rptOwnerStreet2>2628 PEARL ROAD</rptOwnerStreet2>
            <rptOwnerCity>MEDINA</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>44256</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>false</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <ownerSignature>
        <signatureName>/s/ Gregory J. Dziak, as attorney-in-fact for Thomas C. Gentile, III under Power of Attorney</signatureName>
        <signatureDate>2026-04-23</signatureDate>
    </ownerSignature>
</ownershipDocument>