A two-dimensional (2D) transient model was developed to simulate the local hydrodynamics of a gas (flue gas)-solid (CaO)-solid (CaCO3) three-phase fluidized-bed carbonator using the computational fluid dynamic method, where the chemical reaction model was adopted to determine the molar fraction of CO2 at the exit of carbonator and the partial pressure of CO2 in the carbonator. This investigation was intended to improve an understanding of the chemical reaction effects of CaO with CO2 on the CO2 capture efficiency of combustion flue gases. For this purpose, we had utilized Fluent 6.2 to predict the CO2 capture efficiency for different operation conditions . The adopted model concerning the reaction rate of CaO with CO2 is joined into the CFD software. Model simulation results, such as the local time-averaged CO2 molar fraction and conversion of CaO, were validated by experimental measurements under varied operating conditions, e.g., the fraction of active CaO, chemical reaction temperature, particle size, and cycle number at different locations in a gas-solid-solid three-phase fluidized bed carbonator. Furthermore, the local transient hydrodynamic characteristics, such as gas molar fraction and partial pressure were predicted reasonably by the chemical reaction model adopted for the dynamic behaviors of the gas-solid-solid three-phase fluidized bed carbonator. On the basis of this analysis, capture CO2 strategies to reduce CO2 molar fraction in exit of carbonator reactor can be developed in the future. It is concluded that a fluidized bed of CaO can be a suitable reactor to achieve very effective CO2 capture from combustion flue gases. (C) 2010 Elsevier Ltd. All rights reserved.