An ultrafiltration hollow fiber enzymatic membrane reactor was employed to study the kinetics of lipase-catalyzed kinetic resolution of racemic ibuprofen ester. Lipase from Candida rugosa was employed in the hydrolysis reaction both in free form in a batch system and in immobilized form in an enzymatic membrane reactor (EMR). The half life (t(1/2)) of immobilized lipase on spongy layer was 105 h at reaction temperature of 40 degrees C and 62 h at 45 degrees C. This value was 94 h for lipase immobilized on the inner lumen and 45 h for free lipase in batch system at 40 'C. Excessive substrate was found to inhibit the reaction as an uncompetitive inhibitor. The by-product 2-ethoxyethanol was found to be non-competitive inhibitor to the reaction when it was present in an excess. Michaelis constant (Km) and maximum reaction rate (V-max) for immobilized lipase were 36.47 mmol L-1 and 3.27 mmol L-1 h(-1), respectively; and that for free lipase were 63.43 mmol L-1 and 2.83 mmol L-1 h respectively. (c) 2005 Elsevier Ltd. All rights reserved.