Polyvinyl alcohol (PVA) membrane (4 wt.%) was modified by lithium chloride (0.05-0.2 wt.%) to investigate the effect of addition of alkali salt on separation of water-isopropyl alcohol mixture. The surface of casted membranes was subsequently cross-linked by exposure to low-pressure nitrogen plasma. The separation performance of modified membrane was analyzed by pervaporation technique at 25 ° C, showing improvement in the flux and the selectivity for purification of water molecules. Characterization of modified membranes was performed by using Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetery (DSC) and the wide-angle X-ray diffraction (WAXD) techniques. It has been identified that the membrane becomes semicrystalline to amorphous by addition of lithium chloride to PVA, affecting the separation performance. © 2005 Elsevier B.V. All rights reserved.