Multi component equilibrium isotherms for the adsorption of propane, n-butane, and i-butane mixture on 5A zeolite at 303 K were obtained experimentally and theoretically. The constant-volume method was used for measuring the experimental equilibria data. Both the extended Freundlich and modified extended Langmuir equations correlated the multi component experimental data fairly well. The selectivity of 5A zeolite to adsorb gases was also studied. The results of this study showed that n-butane was more selectively adsorbed than propane on 5A zeolite, while i-butane was not adsorbed on this zeolite at the studied temperature. Also, it was found that an increase in partial pressure of n-butane decreases the adsorbed amount of propane, while the increase of partial pressure of propane has no effect on adsorbed amount of n-butane. (C) 2011 Elsevier B.V. All rights reserved.