Sorption and dilation isotherms and diffusion coefficients for the polysulfone/CO2 system were measured concurrently. The sorption parameters, the partial molar volume of sorbed CO2 and the concentration dependence of the diffusion coefficient were obtained for the temperature range 15-75 degrees C. The sorption parameters were well related to the temperature, whereas the partial molar volume exhibited no significant temperature dependence. The diffusion coefficient apparently increased with increasing concentration and at the limit of zero concentration its temperature dependence obeyed the Arrhenius equation. The calculated mean permeability coefficient for CO2, based on the concentration dependence of the diffusion coefficient and sorption parameters measured at pressures not higher than 2.5 atm, agreed well up to 20 atm with reported experimental results.