Ethanol steam reforming with/without co-fed oxygen and hydrogen over Ni on high surface area (HSA) CeO2 support, synthesized via a surfactant-assisted method, (Ni/CeO2 (HSA)) was studied under solid oxide fuel cell (SOFC) operating conditions for later application as an instack reforming catalyst. The catalyst provides considerably higher reforming reactivity and excellent resistance towards carbon deposition in comparison with Ni/Al2O3 and Ni on conventional ceria (Ni/CeO2 (low surface area; LSA)). At the temperature above 800 degrees C, the main products from the reforming processes over Ni/CeO2 (HSA) were H-2, CO, and CO2 with some amount of CH4 depending on the inlet steam/ethanol and cofed reactant (i.e. O-2 and H-2)/ethanol ratios, whereas high hydrocarbon compound i.e. C2H4 was also observed from the reforming of ethanol over Ni/CeO2 (LSA) and Ni/Al2O3. An addition Of O-2 (as oxidative steam reforming) and H-2 significantly reduced the degree of carbon deposition. The presence of both reactants also promoted the conversions of hydrocarbon presented in the system (i.e. CH4 and C2H4) to CO and H-2. The major consideration of these additions is the suitable co-fed reactant/C2H5OH ratio. The presence of too high oxygen concentration could oxidize Ni particles to NiO, which resulted in a lower reforming reactivity, and also combusts H-2 to H2O. The suitable O-2/C2H5OH molar ratio for the oxidative steam reforming of Ni/CeO2 was 0.4, which is less than that of Ni/Al2O3. An addition of too high hydrogen content slightly decreased the catalyst activity, which could be due to the active site competition of nickel particle and the inhibition of gas-solid redox reactions between the gaseous hydrocarbon components with the lattice oxygen (O-O(x)) on the surface Of CeO2 support in the case of Ni/CeO2. (c) 2007 Elsevier B.V. All rights reserved.