p- and o-chloromethylbenzoic acid phenyl esters and thiophenyl esters of the formula ##STR1## wherein X represents oxygen or sulfur and R the radical of a mononuclear or polynuclear phenol or thiophenol which is unsubstituted or which bears additional substituents which may include the substituent ##STR2## wherein X is as above. The components can be produced by reacting p- or o-chloromethylbenzoyl chloride with univalent or polyvalent, mononuclear or polynuclear phenols or the thiophenols in the presence of inert solvents and tertiary amines in a catalytic or stoichiometric amount, amides in a catalytic amount, or in an aqueous alkaline medium.