An organic-inorganic composite membrane was successfully prepared by means of electrostatic self-assembly of polyelectrolytes on silica sol-gel modified macroporous ceramic supports. The integrality of the as-prepared composite membrane was evaluated in pervaporation of ethanol/water mixtures. Membrane separation performance was optimized by studying the modification cycle, polyclectrolyte molecule structure, self-assemble conditions, thermal treatment conditions and operating temperatures. It was found that the polyelectrolyte molecule structure mainly affected the separation performance of the composite membrane after a two-cycle modification and raising pervaporation operating temperature was an efficient way to improve both membrane flux and water selectivity. The composite membrane deposited by 60 layer pairs of polyethylenimine/poly (vinyl sulfate) (PEI/PVS) showed a high flux of 18.4 kg m(-2) h(-1) and a water concentration enhancement from 6.2 to 35.3 wt.%. Our study demonstrates that the composite membrane prepared on macroporous ceramic support through our route is suitable for separation of liquid species at a molecular level. (c) 2007 Elsevier B.V. All rights reserved.