Sorption equilibria and permeation rates for oxygen and carbon dioxide in polycarbonate membrane were measured at different temperature between 30 and 60℃ and at pressures up to 2.5MPa. The pressure dependence of mean permeability coefficient to oxygen obeyed the conventional dual-mode mobility model, whereas that to carbon dioxide followed a modified dual-mode mobility model with concentration-dependent diffusivities, as that of polystyrene to the same gas did.