The separation of solutions containing non-polar solvents, like toluene, was found to be limited for PDMS membranes, which is due to the extensive swelling of PDMS in those solvents. To improve the performance of silicone-based membranes for separations in non-polar solvents, extra cross-linking was introduced via the introduction of fillers. Of all fillers tested, zeolites were most efficient in decreasing the swelling of the PDMS network. Zeolites induce an increased cross-linking density, which is explained by the interactions between the silanol-groups of the filler and the PDMS-chains. The performance in SRNF of filled and unfilled PDMS membranes were compared, demonstrating increased solute rejection in non-polar solvents and at higher temperatures upon filler addition. (c) 2005 Elsevier B.V. All rights reserved.