A series of organic-inorganic hybrids were developed via intercalation process of primary, secondary and tertiary ammonium cations into different alkali and alkaline earth and transition metal cation forms of bentonite clay to be used as adsorbent materials for CO2 capture under ambient temperature and slightly high pressure. The effect of the molar mass of amines on the structural characteristics, surface properties and CO2 loading capacity of bentonite clay were investigated by X-ray diffraction, Brunauer-Emmett-Teller method and Magnetic Suspension Balance equipment, respectively. X-ray diffraction results revealed that the basal spacing of bentonite clay after modification with amines was increased with the molar mass of amine used, while BET results showed an inverse effect of the molar mass of amines on the surface area of the synthesized materials. The CO2 loading capacity of the examined samples revealed that bentonite clay modified with monoethanolammonium cations retained higher CO2 amount compared to those modified with di- and triethanolammonium cations. CO2 adsorption isotherms on MEA+-Mg-MMT were conducted at 298, 323 and 348 K and different pressures. A decrease in CO2 uptake with increasing temperature was observed, suggesting the exothermic nature of the adsorption process. © (2014) Trans Tech Publications, Switzerland.