Material characterization is a crucial step to ensure the characteristics and properties of the samples are comparable to the standard adsorbent and suitable for CO2 adsorption. The objective of this work is to characterize natural calcium based materials for CO2 adsorption which are obtained from waste cockle shells. Characterization analyses are conducted by using XRD, BET and FESEM. Material characterization indicates that raw cockle shell is made up of aragonite and needle-like structure. It is also shown that CaCO3 can be decomposed to CaO through high temperature calcination process. Through physisorption analysis, the samples are classified as mesoporous materials and it is shown that calcined cockle shell is better than raw cockle shell in term of surface area and pore volume. The results proved that calcium based materials could be successfully employed as sorbent for CO2 separation.