The pure polycarbonate (PC) and blends of PC and polysulphone (PSF) of various thicknesses in different concentrations are prepared using the solution cast method. These membranes are irradiated by Swift heavy ions of energy 100 MeV with an ion fluence of 10(6)-10(8) ions/cm(2). The permeability of hydrogen and carbon dioxide is measured from both the sides of the membrane with increasing etching time. These membranes show a larger permeability from the irradiation side than from the reverse side, indicating the formation of conical tracks or an asymmetric membrane. Perm selectivity of hydrogen over carbon dioxide also increases with increasing PSF concentration from both the sides and it was found maximum for the 1:3 (PC:PSF) track-etched membrane. The effect of Ti film on the track-etched membrane also improves the selectivity of hydrogen over other gases. The temperature-dependent gas permeability of FeTi powder doped PC films has shown some lower permeability but better selectivity over track-etched membrane. (C) 2007 International Association for Hydrogen Energy.