Pervaporative separation of methanol-benzene over the satire range (0-100%) is studied with polyacrylonitrile homo-polymer and four of its different co-polymer membranes, i.e. acrylonitrile with 2-hydroxyethylmethacrylate, maleic anhydride, acrylic acid and methacrylic acid, respectively prepared through emulsion polymerization. The effect of co-polymer morphology on sorption of the solutes has been studied. The permeation, selectivity, and flux variation with methanol concentration has been explained using the solubility parameter approach. For this purpose the component group contribution, solubility parameter and interaction parameter values have been employed. All the membranes were stable during experimentation. (C) 2002 Elsevier Science B.V. All rights reserved.