Abstract The pervaporation performance of the silicalite-filled GFT PDMS membrane has been investigated for the separation of binary mixtures of BuOH/water and termary mixture of BuOH/acetone/water at 40°C. These components are relevant to the acetone-butanol-ethanol (ABE) fermentation process. In the range of concentrations of industrial interest ( C <- 2.5 wt%), the water flux was almost constant whereas the alcohol fluxes varied linearly with the alcohol concentration for the 4 butanol isomers. Furthermore, no synergy or coupling effect involving acetone (a Lewis base) could be detected within the range of concentrations investigated. It was found that for a given type of membranes the alcohol fluxes correlated with the alcohol polarity parameters in the Reichardt and Dimroth scale. Comparison between the two composite GFT PDMS membranes, filled or unfilled, revealed an important effect of the filler incorporation. Compared to the properties of the unfilled membrane, the fluxes for the filled membrane were usually lower but the gain in selectivity was significant, especially for the pervaporation of ternary feed mixtures relevant to the ABE fermentation process.