Kinetically controlled enzymatic syntheses of cefaclow with D-(-)-phenylglycine methyl ester (PGME) and 7-aminodesacetoxymethyl-3-chlorocephalosporanic acid (7ACCA) were carried out by penicillin acylase.The product yield was improved by the continuous removal of product from the reaction mixture via complexation of cefaclor with 1-naphthol.In situ product removal (ISPR) decreased the product concentration in the bioreactor,consequently the product yield was improved about 21%.The effects of pH,temperatures and substrate concentrations on the enzymatic conversion of cefaclor were investigated.