Two types of Sorbents are investigated here (natural limestone and high), reactive calcium aluminate pellets) to elucidate their reactivity in terms of sulphation and carbonation and determine the resulting effect on looping cycles for CO2 capture. The sorbents are tested in a thermogravimetric analyzer (TGA) apparatus using typical synthetic flue gas mixtures containing 15% CO2 and various Concentrations of SO2. The sulphation and carbonation conversions were determined during sulphation/carbonation/calcination cycles. The sorbent morphology and its changes were determined by means of a scanning electron microscope (SEM). The results showed that Sulphation, that is, the formation of CaSO4 at the sorbent surface, is it cumulative process with increasing numbers Of reaction cycles, which hinders sorbent ability to capture CO,. In the case of high sorbent reactivity, as determined by its Morphology, the unfavorable effect of sulphation is more pronounced, Unfortunately, any increase ill the temperature ill the carbonation stage accelerates sulphation more than carbonation as a result of higher activation energy for the sulphation reaction. The SEM analyses showed that although sulphation and Carbonation occur during cycles involving calcination, an unreacted core/partially sulphated shell sorbent particle pattern is formed. The main outcomes of this research indicate that special attention should be paid to the sulphation when more reactive and more expensive, synthetic CaO-based sorbents are used for CO2 capture looping cycles. Desulphurization Of flue gas before CO, capture appears to be essential because CO, looping cycles dire so strongly affected by the presence of SO,,