Thin a-SiOxCyHz film membranes were deposited from hexamethyldisiloxane precursor on ester of cellulose porous substrates at low-frequency plasma conditions. The sorption properties of the films were measured for CH4, C2H6, C3H8, n-C4H10 and i-C4H10 by using a gravimetric method with a quartz microbalance. The gas permeability coefficients were determined by using the constant-volume pressure-increase method. Correlations were established between the physical parameters of the penetrants and the corresponding sorption, permeation and diffusion coefficients observed. (C) 2003 Elsevier Science B.V. All rights reserved.