A carboxymethyl cellulose acetate (CMCA)/cellulose acetate (CA) blend ultrafiltration (UF) membrane was prepared via phase inversion in the absence and presence of 2.5 wt.% additive, namely polyethylene glycol 600 (PEG 600). CMCA was firstly synthesized from carboxymethyl cellulose sodium (CMC-Na) by acidifying and esterifying. The as-prepared blend membranes were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), mechanical analysis, contact angle, pure water flux (PWF), water content (WC), rejection and molecular weight cut off (MWCO) to understand the influence of polymer blend composition and additive on the properties of the modified membranes. SEM and AFM surface roughness analysis showed that CA/CMCA blend membranes possessed large size pore in the top layer and porous structures in the cross-section. Compared to the pure CA membrane, blending of CA with CMCA resulted in novel blend membranes with enhanced ultrafitration membrane characteristics such as lower contact angle and higher PWF coupled with higher water content. Bovine serum albumin (BSA) was subjected to rejection by the blend membranes. Meanwhile, the fouling resistant ability was studied and the UF experiments suggested that the modified membranes had more positive influence on membrane anti-fouling performance. (c) 2012 Elsevier B.V. All rights reserved.