The permeation of various mixtures of pentane-decane and pentane-dodecane through dense PDMS/PAN membranes has been measured in a cross-flow membrane cell for pressures varying from 10 to 40 bar. The results have successfully been modeled with both the solution diffusion with imperfections model and the Maxwell-Stefan transport equation taking into account both diffusive and viscous flow. The modeling with the Maxwell-Stefan transport equation gave more realistic values of the estimated parameters. Increasing the pentane concentration in the feed solution reduces the percentage diffusive flow due to the increasing swelling of the membrane. (c) 2006 Elsevier B.V. All rights reserved.