Dense polyion complex membranes of anionic sodium alginate (NaAlg) and cationic polyethyleneimine (PEI) were prepareand crosslinked with glutaraldehyde for dehydration of alcohol-water mixtures by pervaporation (PV). The membranes were characterized by ion-exchange capacity measurement, Fourier transform infrared spectroscopy, differential scanning calorimetry and scanning electron microscopy to investigate the extent of cross-linking, intermolecular interactions, thermal stability, and surface and cross-sectional morphologies, respectively. Wide-angle X-ray diffraction was used to investigate the crystallinity of the membranes. PV dehydration characteristics of the membranes were determined as a function of PEI content, crosslinking time as well as feed water composition. Transport parameters such as sorption, diffusion and permeability of water and alcohols through the membranes were determined. Among the four different membrane compositions, the polyion complex containing 40% PEI was found to yield optimum separation data in terms of membrane stability, selectivity and permeability. On the other hand, 10% PEI-containing membrane gave the highest selectivity with the lowest flux at ambient temperature, but the membranes were not sufficiently stable. (C) 2007 Society of Chemical Industry