In this study, polyelectrolyte complex (PELC) membranes prepared by the Simultaneous interfacial reaction between aqueous solutions of sodium cellulose sulfate (NaCS) as polyanion and poly(dimethyldiallylammonium chloride) (PDMDAAC) as polycation were proposed. The preparation conditions were optimized. The influence of two important factors, molecular weight (MW) of PDMDAAC and reaction time on the membrane formation procedure and permeability was investigated. Membranes with the preparation conditions as NaCS 3.5% (w/v), PDMDAAC (MW = 200-350 kDa) 70% (w/v), the reaction time 30 min, hold a favorable performance, and steady state in water flux experiment. To testify the feasibility of the membrane used in salt separation, membrane performances and selectivity of the inorganic salts as well as their relations to the preparation conditions, the operation parameters, the species of inorganic salts, etc., were investigated in the pressure-driven experiments. The results showed that this single-layer PELC membrane afforded higher rejections of divalent ions (SO42-) to that of monovalent ions (Cl-), which indicated the potential application of this membrane system in the salt rejection process. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 112: 402-409, 2009