We studied ethanol steam reforming over Ir/Ce(0.9)Pr(0.1)O(2) and Ir/CeO(2) catalysts comparatively with respect to activity and stability. We found that PrO(x)-doping have significantly promoted the oxygen storage capacity and thermal stability of the catalysts by incorporation into the ceria lattice. Ethanol was readily converted to hydrogen, methane and carbon oxides at 773 K over the Ir/Ce(0.9)Pr(0.1)O(2) catalyst, and this is 100 K lower than that found for the Ir/CeO(2) catalyst. Moreover, the PrO(x)-doped catalyst was stable toward ethanol steam reforming at 923 K for 300 h without an apparent variation in ethanol conversion and product distribution. However, the severe aggregation of ceria particles and heavy coke deposition were observed on the Ir/CeO(2) catalyst, resulting in remarkable deactivation under the same reaction conditions. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.