Various materials have been used as supports for the immobilization of a Candida rugosa lipase (Lipase OF). The enzyme adsorbed on silica gel showed the maximum activity recovery (37%), and was thus used to construct a packed bed reactor for the continuous production of (S)-ketoprofen. The performance of the bioreactor containing 4.0 g immobilized biocatalyst was evaluated as a function of parameters such as flow rate, the ratio of height to diameter (H/D) and substrate concentration. The space velocity (SV) of the reactor showed a linear increase when the flow rate was increased in the range of 5.9 (SV = 0.9 h(-1))-25 ml h(-1) (SV = 3.9 h(-1)) and leveled out at values for flow rate between 25 (SV = 3.9 h(-1)) and 64 ml h(-1) (SV = 10.2 h(-1)). The initial rate remained the same when the H/D was varied from 2.9 to 38.6. The initial rate rose in a linear fashion as the substrate concentration was increased from 5 to 20 mg ml(-1) and remained almost at the same level when the substrate concentration was between 20 and 50mg ml(-1). Using a packed bed bioreactor, optically pure (S)-ketoprofen (> 99% ee (enantiomeric excess)) was produced with a conversion of 30% and productivity of 1.5 mg g(-1) biocatalyst h(-1). (c) 2004 Elsevier Ltd. All rights reserved.