A process for preparing CO with CO2 as gasification agent and rice husk as raw material in the presence of metal oxide catalyst was reported in this paper. Five kinds of catalysts (Fe2O3, CoO, NiO, CuO, and ZnO) supported on gamma-Al2O3 were compared in the catalytic gasification, and the effects of reaction temperature, system pressure, catalyst loading, space velocity, and rice husk particle size were also studied. The results show that ZnO/gamma-Al2O3 obtained at a calcination temperature of 650 degrees C exhibits the highest activity. The optimal conditions are: 800 degrees C, 0.1 MPa, ZnO loading of 7.5%, space velocity of 240 h(-1), and rice husk particle size of 0.20-0.30 mm. Under such conditions, 22.1% of CO content, 22.4% of CO2 conversion, and 71.7% of rice husk conversion are obtained. (C) 2015 Elsevier B.V. All rights reserved.