Several active membranes were prepared by immobilization of Candida antarctica lipase B (CALB) onto the surface of ceramic membranes via three different ionic liquids (ILs): [bmim(+)][PF6-], [emim(+)][NTf2-] and [bmim(+)][NTf2-] and compared to an active membrane obtained by simple enzyme adsorption. The performances of these various membranes were evaluated by studying the synthesis of butyl laurate by the acidolysis between butyl acetate and lauric acid in a hexane/water mixture (98:2, v/v). The results obtained show that all the membranes prepared with or without ILs were active and maintained their activity after several runs and during some months. (c) 2005 Elsevier B.V. All rights reserved.