Sulfation of calcium-based sorbent is bound to occur during carbonation or calcination of the sorbent in a calcium looping system if SO2 is present in the system, and it will influence the CO2 capture capacity of the sorbent. While the effect of sulfation during the carbonation stage on the CO2 capture capacity has been studied by some researchers, the effect of sulfation during the calcination stage has not been studied extensively. In this study, the effect of sulfation during the calcination stage under oxy-fuel combustion conditions on the CO2 capture capacity of two calcium-based sorbents was investigated. The results showed that the calcination temperature and O-2 concentration of 5-20% had little effect on the sulfation of the sorbents, while SO2 concentration and the presence of H2O greatly influenced the cyclic performance of the sorbents. Furthermore, reducing calcination time seems to be an effective way to limit sulfation during calcination, because the sulfation rate is slow in the initial induction stage of the gas solid reaction.