A novel experimental approach to determine the solubility, of gaseous compounds inside polymers is here described. The method is based on the gas chromatographic determination of the composition of the fluid phase at equilibrium with the polymer. To take into account the effect of the volume swelling on the measurement a suitable probe, nonabsorbable by the polymer, was added to the fluid phase. Under the adopted configuration the apparatus can operate up to 35 MPa and 80 degrees C This experimental technique has been used to determine the solubility of carbon dioxide in poly(vinylidene fluoride) using argon as a probe. The latter was chosen because it is negligibly absorbed by the polymer and does not significantly alter the chemical potential of CO2. The uncertainty of the method in the determination of the solubility was estimated for each experimental points by error analysis. (c) 2006 American Institute of Chemical Engineers