Experimental data for adsorption of pure carbon dioxide, methane, and nitrogen on zeolite 13X granules at different temperatures (288.15-318.15 K) and pressure up to 20 bar are reported. The cation of adsorbent is exchanged with H+, Li+, and Cu2+, and the adsorption of pure gases is measured. The equilibrium adsorption isotherms of gases are performed with a static volumetric adsorption instrument, which was designed and built. The results show that the adsorption capacity of carbon dioxide is higher than that of methane and nitrogen and that the cation exchange improved the adsorption capacity of pure gases. The LiX adsorbent has the highest adsorption capacity among the studied adsorbents. However, the relative selectivity of carbon dioxide over methane for zeolite 13X has the highest value of 30.48. The CuX adsorbent shows the highest selectivity for carbon dioxide over nitrogen. The adsorption isotherms for all of the pure gases are fitted successfully with the Toth model.