Cellulose acetate (CA) is highly comparable to other synthetic polymer materials and is effective in the hemodialysis process. In this work, asymmetric CA membranes were synthesized with the phase-inversion method. CA with a molecular weight of 52,000, poly(ethylene glycol) (PEG) with a molecular weight of 400, and 1-methyl-2-pyrrolidone (NMP) were used as the polymer, additive, and solvent, respectively. The effects of the CA and PE-G concentrations and coagulation bath temperature (CBT) oil the morphology, pure water permeability (PWP), insulin/hUrnan serum albumin (HSA) transmission, and finally thermal and chemical stability of the prepared membranes were determined and investigated. In general, increasing the PEG concentration and CBT and reducing the CA concentration resulted in increased PWP and insulin/HSA transmission. Also, these variations facilitated the formation of macrovoids in the membrane sublayer. Oil the other hand, increasing the PEG and CA concentrations and reducing CBT resulted in increased thermal and chemical stability of the prepared membranes. Also, ratios of 15.5/10/74.5 and 17.5/10/72.5 for the CA/PFG/NMP casting solutions and their immersion into coagulation baths with CBTs of 0 and 25 degrees C, respectively, resulted in the preparation of membranes that had not only optimum sieving properties and higher PWP but also thermal and chemical stability better than that of conventional CA hemodialysis membranes. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 116: 2251-2259, 2010