In this study, the catalytic activity of nickel supported on Ce0.75Zr0.25-xMnxO2 (x = 0, 0.10, 0.20 and 0.25) mixed oxide catalysts prepared by urea hydrolysis and incipient wetness impregnation was investigated for steam reforming of naphthalene selected as a model compound for biomass-derived tar. The results showed that nickel supported on Ce0.75Zr0.25-xMnxO2 mixed oxide catalysts exhibit good activity for naphthalene steam reforming. It was found that the amount of carbon deposition reduced substantially when Mn was introduced to the CeO2-ZrO2 mixed oxide. This might be due to the fact that the incorporation of manganese ions into the ceria lattice would improve the oxygen storage capacity and the oxygen mobility on the surface of mixed oxides, resulting in enhancing the gasification of the deposited carbon. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.