Abstract: The overwhelming increasing the fuel price and exhausting of fossil fuel resources in Malaysia is alarming, therefore, renewal sources of energy should be further studied. There are attempts in using biomass as renewable energy resources to produce producer gas which can be used as fuel, however, the shortcomings and inefficiencies in the available technology have made it uneconomical. The CO2 in the producer gas which is incombustible from the biomass gasification must be removed to enhance its quality. For that, a device called Bubbling Fluidized Bed CO2 Absorption Reactor (CO2 BFBAR) has to be developed. Calcium oxide (CaO) derived from natural limestone produced in Malaysia (blessed with abundant reserve of limestone resources) can be an effective sorbent to absorb carbon dioxide (CO2) gas at high temperature. In the present study, the simulation of the hydrodynamic characteristics in the CO2 BFBAR is done. The objective is to find out whether the 50% CaO-sand mixture used in the reactor can perform fluidization perfectly without sticking out. The three dimensional geometry and mesh generation of the CO2 BFBAR was build using ANSYS FLUENT CFD software and then the geometry is exported to the Computational Fluid Dynamics (CFD) software called Fluent v6.2.16 for analysis. By applying the constant volume flow rate, Q from 15 to 55 L min-1, the Fluent simulated the bubbling height of CaO-sand material and the bubbling behavior in the CO2 bfbar versus time for three types CaO particle sizes (100, 500 and 1000 μm). After that, the results from the computer simulation analysis are compared to the cold model experiment results. Overall, it shows that the simulation results give a good agreement with the experiment results. The percentages difference obtained for three types CaO particle sizes, are below than 5.3%. All results obtained have been used to design the CO2 BFBAR.