A non-local density functional theory (NDFT) in combination with the pore size distribution (PSD) analysis has been applied to make a comprehensively theoretical study for correlating and predicting the adsorption equilibria of pure supercritical gases and the corresponding binary supercritical gas mixtures on activated carbon. In this approach, the required PSDs were determined from an input of experimental adsorption data of pure components. By comparing with the experimental data of three different binary systems, CH4/N-2, CH4/CO2, and CO2/N-2, at high pressure up to 13.6MPa and temperature 318.2K with various concentration ranges, the predictive performance of the theoretical approach was evaluated. The adsorption of the mixtures has also been predicted by applying the ideal adsorbed solution (IAS) theory. It was shown that the NDFT/PSD method could be used to predict the mixture adsorption behaviors under high pressure. The developed method has greater superiority over the IAS theory in the prediction of the mixture adsorption. (c) 2005 Elsevier Ltd. All rights reserved.