This article describes the reactive kinetics of nano-CaO with CO2 in a sorption complex catalyst. Based on an observation of nano-CaO reaction with CO2 has a fast surface reaction regime and followed by a slow diffusion-controlled regime, a criterion has been proposed to divide the fast surface reaction regime and the slow diffusion-controlled reaction regime. The kinetics of the fast surface reaction was studied, and a new ion reaction mechanism was proposed. A surface reaction-controlled kinetic model with a Boltzmann equation, X = Xu-Xu/[1+exp((t-t0)k/Xu)], was developed. Experiments using nano-CaO to react with CO2 in a fast surface reaction regime within a sorption complex catalyst were performed using thermogravimetric analysis at 773873 K under a N2 atmosphere with 0.0100.020 MPa CO2. The activation energy of the kinetic model for carbonation is 30.2 kJ/mol, and the average relative deviation of the sorption ratio is less than 9.8%. (c) 2011 American Institute of Chemical Engineers AIChE J, 2012