Chain-length selectivity profiles of seven lipases (EC 3.1.1.3) have been determined by multiple substrate competition for three reactions at 30 and 50degreesC: hydrolysis and synthesis of fatty acid methyl esters and acyl transfer between fatty acid ethyl esters and methyl esters. All acyl chains were even-numbered and saturated. Chain-length specificity profiles depended on the enzyme and the reaction considered, due to the combined influence of enzyme and substrate properties. Changing temperature had a significant influence on substrate specificity for esterification only. The results led to the selection of Candida deformans lipase for the selective hydrolysis of short-chain (C-8, C-10) esters in an equimolar mixture of C-8-C-18 methyl esters in the presence of various methanol concentrations. The reaction resulted in a long-chain-enriched methyl ester and a short-chain-enriched fatty acid fractions, respectively, consisting of 96% C-12-C-18 and 68% C-8-C-10 in a given example.