A laboratory prepared PDMS-membrane was used as a reference material to elucidate the transport mechanism for solvent resistant nanofiltration (SRNF). Together with the commercially available MPF-50 membrane, its physico-chemical properties were first well characterised by means of FEG-SEM and elemental analysis of the top-layer (XPS). Compaction was studied in order to allow a correct interpretation of the data obtained from the filtration of several solvents through these membranes. A tentative physico-chemical interpretation of the transport mechanism of solvents through both membranes was finally formulated. (C) 2003 Elsevier B.V. All rights reserved.