For dehydrating aqueous acetic acid solution by pervaporation, a poly (4-methyl-1-pentene)/Co(III) (acetylacetonate), TPX/Co(acac)(3), blend membrane was synthesized. The effects of Co(acac)(3) content, feed compositions, feed temperature, and degree of swelling on pervaporation performance were investigated. The stability of the blend membrane was examined by ultraviolet study. Water molecules preferentially dissolve in the TPX/Co(acac)3 membrane and also predominantly diffuse through the membrane. A separation factor for water of 154 and a 163 g/m(2)-h permeation rate with a 10 wt% Co(acac)(3) content TPX/Co(acac)(3) blend membrane for pervaporation of 80 wt% acetic acid feed concentration were obtained. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.