Lipase (EC 3.1.1.3) was immobilized on cellulose acetate-TiO2 gel fibre by the sol-gel method. The immobilized lipases were used for esterification of n-butyric acid with n-butyl alcohol and enantioselective acylation of (R, S)-phenylethanol using vinyl acetate as an acyl donor. Compared with native lipase, the activity of the immobilized lipase was stable and relatively unaffected by the water content of the solvent and the substrate concentration. The data indicate that the lipases are immobilized on the fibre surface and that enzyme activity is influenced by bound water. However, the thermal reactivity and enantioselectivity of the immobilized lipase were less than those of native lipase. This may not reflect thermal inactivation of the enzyme but rather significant thermal contraction of the gel fibre by cellulose crystallization, resulting in liberation of bound water and a decrease in the amount of enzyme which is available for the reaction. Copyright