BACKGROUND: In the present study, the kinetic resolution of rac-1-phenylethanol by transesterification with several vinyl esters catalysed by a commercial immobilized Candida antarctica lipase B (Novozym 435) was carried out in n-hexane at different water contents. The subtrates and products involved in the kinetic resolution were separated using a membrane bioreactor containing a supported liquid membrane based on the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate [bmim(+)][BF4-]. RESULTS: Variables affecting the kinetic resolution performance of the enzyme were studied. First, the influence of water content of the medium on the synthetic activity, selectivity and enantioselectivity of the enzyme was analysed in order to establish the optimal amount of water. The use of vinyl esters of different alkyl chain length (vinyl propionate, vinyl butyrate and vinyl laurate) as acyl donors to kinetic resolution was studied. Finally, the integrated reaction/separation process for the resolution of rac-1-phenylethanol was carried out in the optimal conditions found. CONCLUSION: These investigations demonstrate that the coupling of lipase enantioselectivity with the selective separation of supported liquid membranes based on ionic liquids provides a promising basis for practical production of enantiomerically pure or enriched compounds. (C) 2008 Society of Chemical Industry