Surfaces of polyelectrolyte complex membranes based on sodium cellulose sulfate and poly(dimethyldiallylammonium chloride) were studied by means of XPS photoelectron spectroscopy (ESCA), contact angle and tangential streaming potential measurements. The results of this study are discussed from the point of view of the membrane formation conditions as well as their efficiency and selectivity under pervaporation conditions. Several important relations have been found between surface characteristics, polyelectrolyte complex formation conditions and membrane performances.