Department of Chemistry, Faculty of Science, University of Tanta, Tanta, Egypt Manuscript received 5 Ju!y 1979, accepted 28 January 1981 The kinetics of the catalyzed hydrolysis of binary mixtures or ethyl acetate/polyvinyl acetate, n-butyl acetate/isobutyl acetate and n-propyl acetate/n.-butyl acetate was studied in presence of Wofatit KPS resin. In the first mixture polyvinyl acetate was excluded by sieve action, the reaction was first order with respect to ethyl acetate. A preference for the straight-chain over the branched-chain molecule was observed in the second mixture. The reaction was zero order for both esters in the mixture. In the third mixture the resin hydrolyzed both esters with comparable rates, both the rates affected one another. In the latter case the mechanism changed during the same reaction, the order was zero with respect to the ester whose hydrolysis reaction was the rate