Adsorption isotherms of carbon dioxide were measured on cation-exchanged (Li + , Na + , K + , Cs + ) MCM-22 zeolite with the molar ratio of Si/Al = 15 and series of Na-MCM-22 of Si/Al molar ratios varying in the range from 15 to 40 at 273, 293, 313 and 333 K. Based on the known temperature dependence of CO 2 adsorption, isosteric heats of adsorption were calculated. The obtained dependences of isosteric heats related to the amount of CO 2 adsorbed have provided detailed insight into the interaction of carbon dioxide molecule with alkali metal cations.Keywords MCM-22 zeolite · Alkali metal cation exchange · CO 2 adsorption · Isosteric heat of adsorption Abbreviations S BET BET surface area, m 2 /g S external external surface area, m 2 /g V total total pore volume, cm 3 /g V micro micropore volume, cm 3 /g q st isosteric heat of adsorption, kJ/mol R gas constant, kJ/mol·deg