Zeolite X/activated carbon composite adsorbent was made from amorphous sodium aluminosilicate that was obtained from the silica of rice hulls and sodium aluminate in pores of granules. The experimental data of CO2 and water adsorption on zeolite X/activated carbon composite was fitted by various isotherm models such as Langmuir, Toth and Langmuir-Freundlich, excess surface work(ESW) models. The Langmuir-Freundlich, Toth model represented the equilibrium data fairly well within 2% average relative deviation. The ESW model could be successfully applied for description of water adsorption isotherm over whole pressure region.