Dialysis membranes were casted from solutions containing 20 wt.% cellulose acetate (CA), various concentrations of monosodium glutamate (MSG) and formic acid. Effect of MSG and different molecular weights of cellulose acetate on membrane permeability was investigated. As the MSG concentration increased from 2 wt.% to 6 wt.%, the uremic toxins permeability was enhanced, but further increase beyond this point did not improve the permeability performance. Similar separation trend was observed regardless of the CA molecular weight used, but membranes produced form high molecular weight CA membrane exhibit better uremic toxic permeability. SEM images illustrated that MSG influences the membrane thickness and macrovoids formation, while high molecular weight CA tends to suppress the size of the macrovoids. MSG also tends to reduce the membrane resistance promoting the formation of porous structure and thus explained for high ultrafiltration rate (UFR). In order to gain more insight on the influence of both MSG and molecular weight of CA on membrane properties, the membrane surfaces were analysed using Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR), contact angle measurement (CAM), atomic force measurement (AFM). In addition, mechanical test and thermal stability studies were performed in this study to evaluate the strength of the membranes. In short, MSG and high molecular weight CA played crucial roles in enhancing the separation performance. (C) 2010 Elsevier B.V. All rights reserved.