Modified sorbents - produced by adding compounds of Mg2+, Sr2+ and Al3+ to calcium oxide - have been tested in terms of their CO2 sorption/desorption performance in a fixed bed reactor at high temperatures. In particular this study focuses on the stability of the sorbents as well as the sorption capacity, both of which are important factors when selecting sorbents. X-ray diffraction (XRD) and scanning electron microscope (SEM), coupled with energy dispersive X-ray spectroscopy (EDX), were used for characterization of the modified sorbents. XRD results indicated that samples produced using the wet mixing process and those produced using the hydration with wet mixing process, contained MgO-CaO, Ca0.2Sr0.8O-CaO and Ca12Al14O33-CaO phases, respectively. The operating conditions have been investigated and results showed that the CaO showed the highest sorption capacity (0.571gCO2/gsorbent) when compared with MgO, SrO and Al2O3 at temperature of 600°C. In terms of sorption capacity performance for sorbents produced by the CaO hydration and wet mixing method, Mg-CaO-HW showed the best sorption/desorption stability for more than 10 cycles (CO2 sorption capacity of 0.259 for 1st cycle to 0.252gCO2/gsorbent for the 10th cycle). Al-CaO-HW and Sr-CaO-HW exhibited a decrease in sorption capacity due to the sintering as confirmed by SEM images (0.257 and 0.286gCO2/gsorbent for 1st cycle dropping to 0.243 and 0.251gCO2/gsorbent for 10th cycle resulting in decreasing approximately of 5.45% and 12.24%, respectively).