Chitosan composite membranes were prepared by casting solution onto a porous polyethersulfone ultrafiltration membrane with various surface crosslinking densities. Pervaporation performance of water-alcohol mixtures through the surface crosslinked chitosan composite membranes exhibited a high selectivity value with a low permeation flux. By increasing feed ethanol concentration, permeate flux decreased and water concentration in the permeate decreased drastically at a feed ethanol concentration above 97 wt%. Permeation rate of chitosan composite membranes :is less temperature-dependent than that of PVA. IPA-water mixture has a similar tendency as that of ethanol-water mixture in pervaporative dehydration performances.