In this study, the preparation of polyimide composite membranes was investigated by the electron beam (EB) irradiation method. The asymmetric polyimide membranes as substrates were prepared on the non-woven fabric by the phase inversion process. Electron beam irradiation was done on the polyimide membrane using the EB irradiation equipment with low acceleration voltage (50 keV) in the nitrogen atmosphere. Graft polymerization took place by soaking membranes after the EB irradiation in aqueous ethanol solution with various vinyl monomers. The performance of prepared membranes was evaluated by nitrogen permeability and by flux and separation factor for a benzene/cyclohexane (50/50, w/w) azeotropic mixture at 30degreesC on pervaporation. (C) 2003 Elsevier B.V. All rights reserved.