The reversible carbonation and calcination of calcium oxide with CO2 provide potential for capture of CO2 from high temperature gas stream. An important issue of calcium oxide based sorbents is how fast and to what extent carbonation and calcination take place and how they progress in multi cycles. We show here the mechanism determining their behaviors. Structure promoted sorbents were also investigated to try to overcome performance degradation. The CO2 uptake at various temperatures was determined by thermogravimetric analysis. To study the reversibility of the sorbents, multiple cyclic operations were performed at realistic conditions.