d Carbon dioxide captured by various porous materials has received the most attention due to its contribution in rising atmospheric temperatures. Therefore there is a keen interest in developing materials and processes that can efficiently and economically capture and isolate carbon dioxide. We are reporting on porous synthetic hectorites for selective adsorption of CO2 over N-2, CO, CH4 and O-2. Synthetic hectorites were synthesized with and without an organic modifier (tetraphenylphosphonium bromide), subsequent removal of the organic modifier by calcination resulted in porous synthetic hectorites having variable pore diameters. The prepared synthetic hectorites gave higher surface area, pore volume and pore diameter. Synthetic hectorites were characterized by powder X-ray diffraction which confirmed the formation of layered structures. Synthetic hectorite showed very good selectivity for CO2 over N-2, CO, CH4 and O-2 at both 288 and 303 K. The dynamic adsorption/desorption of CO2 and N-2 mixture over porous synthetic hectorites was also performed.