In this study, we report on the gas permeability of non-polymerized and polymerized fullerene films (thickness about 0.5 mu m) grown on an organic polymer substrate, polycarbonatesyloxane (PCS), using a high vacuum deposition method. The photopolymerized C-60 films were prepared by a simultaneous thin film deposition and UV-vis irradiation method which was reported previously [V.A. Karachevtsev, P.V. Mateichenko, N.Y. Nedbailo, A.V. Peschanskii, A.M. Plokhotnichenko, O.M. Vovk, E.N. Zubarev, A.M. Rao, Carbon 42 (2004) 2091]. Raman spectroscopy revealed that similar to 90% of the C-60 molecules are covalently linked to neighboring C-60 molecules in the photopolymerized film after 20 h of film deposition/irradiation. Permeability of the resulting membranes consisting of polymer PCS base and fullerene films to the N-2, O-2, CH4, and He gases has been investigated. Our experiments revealed that the gas permeability properties are dependent on the age of the membrane. In particular, the aged membrane exhibited an enhanced permeability for O-2 and He gases in comparison to N-2 and CH4, respectively. (c) 2006 Elsevier B.V. All rights reserved.