A novel approach to the evaluation of the C-1-C-4 hydrocarbon (pure and mixed-gas) permeability parameters in the thin film composite membranes with rubbery or glassy-like selective layers is presented. The permeability measurements are performed for the C-1-C-4 hydrocarbons on the commercially available membranes MDK (based on polydimethylsiloxane (PDMS)) at the temperature range of -20 degrees up to +40 degrees C under linear heating. The values of the gas permeability coefficients P and the apparent activation energy E-P were measured during same experiment. The solubility data (S and Delta H-S) were calculated using the Pierotti's statistical-thermodynamic model. The diffusion coefficients were calculated indirectly using the permeability and solubility data assuming the solution-diffusion model for permeation. The equal data sets were obtained for the polyisoprene membranes and the polyvyniltrimethylsilane ones. It is concluded that the ideal C-1-C-4-hydrocarbon separation selectivity is controlled by the kinetic component (selectivity of diffusion). The article also describes the permeability increase of propane, butane (pure and in mixtures) under the temperature pull down in the PDMS (being consistent with the lower activation diffusion energy E-D of those hydrocarbons in the typical rubber-like polymeric matrix which is a thin selective layer). The results of this study will be useful in understanding of the fundamental aspects of the membrane C-1-C-4 separation phenomena, and for the fast separation parameters evaluation of the lower hydrocarbon mixtures using the polymeric membranes as well. (C) 2017 Elsevier B.V. All rights reserved.