Novel catalysts of Ni-Bi/gadolinia-doped ceria (GDC) were employed to perform steam reforming of methane at 700-850 degrees C.The Bi species under the operating condition of this work was mostly Bi2O3. The presence of Bi2O3 enhanced CO2 formation and reduced CO selectivity. Over co-impregnated Ni-Bi/GDC, the formation rate of CO2 plus CO increased with increasing Bi content. The two-step impregnated catalyst had higher reforming activity but also higher CO selectivity than the co-impregnated one. The quantity of Ni-Bi interface is an important factor for enhanced CO2 formation to reduce CO concentration in the product. At 700-800 degrees C, the CO selectivity over co-impregnated Ni-Bi/GDC was at most 1%. (C) 2008 Elsevier B.V. All rights reserved.