Enzymatic conversion of vegetable oils into biodiesel offers an environmentally more attractive option to the conventional processes. However, lipase can be deactivated by lower linear alcohols, such as methanol and ethanol, conventionally used in biodiesel process. In this work, transesterification reactions of waste frying oil were carried out in presence of two different acyl acceptors in order to analyze its influence on the free and immobilized lipase activity. (C) 2010 Elsevier B.V. All rights reserved.