The purified lipase from Pseudomonas cepacia was used as free and immobilized enzyme preparation for hydrolysis of p-nitrophenyl palmitate (pNPP) and p-nitrophenyl acetate (pNPA) in organic media. The free enzyme was mixed with bovine serum albumin and lyophilized. Immobilization was on porous polypropylene. Conditions where diffusional limitations of the substrate were not limiting the reaction rate were defined, The specific activity of the lipase was greatly enhanced upon immobilization : 16.5- and 7.8-fold for pNPP and pNPA respectively. Both the free and immobilized lipases followed Michaelis-Menten kinetics in organic solvent despite the heterogeneity (solid/liquid) of the reaction mixture, For pNPP, the activation factor upon immobilization came mainly from a reduction in K-m.app while k(cat) was increased for pNPA.