Lipase triacylglycerol acylhydrolase, (E.C. 3.1.1.3) is an enzyme that is fully active on aggregated substrates and practically inactive on monodisperse systems. A lipase immobilized on polymeric membranes has been applied for sunflower oil hydrolysis. The influence of membrane properties on enzyme activity is studied. Membranes made of poly(vinyl chloride), collagen, cellulose acetate and polytetrafluoroethylene were used for adsorption of lipase. The porosity and hydrophobicity of membranes did not influence the lipase activity. The difference of the work of adhesion for the water/membrane system and oil/membrane system reflected the activity data, while work of adhesion for water or oil (done separately) did not. For oil hydrolysis to occur on the membrane surface, accessibility of two liquid phases is important, and the lower the difference of work of adhesion between water and oil, the greater the activity of immobilized lipase.