Noble metal (Rh, Pt, Pd, Ir, Ru, and Ag) and Ni catalysts supported on CeO2-Al2O3 were investigated for water gas shift reaction at ultrahigh temperatures. Pt/CeO2-Al2O3 and Ru/CeO2-Al2O3 demonstrated as the best catalysts in terms of activity, hydrogen yield and hydrogen selectivity. At 700 degrees C and steam to CO ratio of 5.2:1, Pt/CeO2-Al2O3 converted 76.3% of CO with 94.7% of hydrogen selectivity. At the same conditions, the activity and hydrogen selectivity for Ru/CeO2-Al2O3 were 63.9% and 85.6%, respectively. Both catalysts showed a good stability over 9 h of continuous operation. However, both catalysts showed slight deactivation during the test period. The study revealed that Pt/CeO2-Al2O3 and Ru/CeO2-Al2O3 were excellent ultrahigh temperature water gas shift catalysts, which can be coupled with biomass gasification in a downstream reactor. (c) 2007 Elsevier B.V. All rights reserved.