Cellulose acetate (CA) and poly(N-vinyl-2-pyrrolidone) (PVP) blend membranes with different compositions were prepared for the pervaporation separation of methanol/MTBE mixtures. The structural morphology, thermal stability and crystallinity of the blend membranes were characterized by FTIR, TGA, DSC and XRD. The effect of PVP content in the blend membranes on the pervaporation performance was investigated and discussed in terms of the sorption and diffusion behavior. The permeation flux was increased by the addition of PVP and the separation factor was also increased when the PVP content was in the range of 10-15 wt.% The effect of operating conditions including the operating temperature, the feed flow rate and the feed composition on the pervaporation performance was extensively investigated. Among all the fabricated blend membranes, the membrane containing 85 wt.% CA and 15 wt.% PVP showed the highest separation factor with a value of 411 and a permeation flux of 430 g m(-2) h(-1) for a feed composed of 20 wt.% methanol at 313 K. (C) 2008 Elsevier B.V. All rights reserved.