Hydrolysis of fatty acid esters with different acyl and alkyl chains in subcritical water was examined over a temperature range of 483-543 K in a batch reactor. The concentrations of fatty acid esters were sufficiently low to assume a homogeneous reaction at every temperature. The hydrolysis of every fatty acid ester at any temperature obeyed first-order kinetics. The rate constant was observed at various temperatures, and the apparent activation energy and frequency factor were evaluated according to the Arrhenius equation for each fatty acid ester. Steric hindrance of the acyl and alkyl chains was found to increase the activation energy of the hydrolysis. The enthalpy-entropy compensation held in the hydrolysis of the fatty acid esters tested. (C) 2003 Elsevier B.V. All rights reserved.