Commercially available zinc perchlorate hexahydrate [Zn(ClO4)(2 center dot)6H(2)O] was found to be a highly e. ffectivecatalyst for the transesteri. cation of malonic esters with alcohols. The treatment of methyl-, ethyl-, or alpha-substituted malonic esters with primary or secondary alcohols in the presence of a catalytic amount of zinc perchlorate results in good to high yields of the corresponding esters (68%-99%). Monotransesteri. cation products are also obtained in moderate to good yields (22%-42%). The reaction was also carried out with 2-mono- and di-substituted malonic esters, and in the case of 2-mono- and di-substituted malonic esters, the reaction time is, in some cases, shorter, in which the yields are comparable with unsubstituted derivatives. The cyanomethyl and bis-cyanomethyl malonic ester derivatives are also used for transesteri. cation and the corresponding products are obtained in high yields. No reaction occurs with the CN group during the reaction.