The preparation and characterization of novel PIM-1/silicalite-1 (MFI) mixed matrix membranes (MMMs) are reported. Silicalite-1 crystals of size 350 nm were synthesized and functionalized with 2-phenylethyl groups to favour a higher hydrophobicity in the PIM-1 matrix. MMMs with different functionalized crystal loadings (from 8.4 to 35.5 v%) were prepared, characterized and tested in the separation of ethanol from aqueous mixtures with different concentration (5 and 9 wt%) via pervaporation. Pure gas transport properties were also measured for the MMM with the highest filler loading. The enhancement in both ethanol/water separation factor (5.7 vs. 4.3) and CO2/N-2 selectivity (30 vs. 24) compared to neat PIM-1 indicates a positive effect of the silicalite-1 on the molecular separations investigated. (C) 2013 Elsevier Ltd. All rights reserved.