Co catalyst supported on BaAL(12)O(19) (BA) showed higher activity in the steam reforming of tar from the pyrolysis of biomass than those supported on Al2O3, ZrO2, SiO2, MgO, and TiO2. Characterization results indicate that the Co metal particles supported on BA had high dispersion, although the surface area of Co/BA was small. High dispersion of Co metal particles on BA can account for the high steam reforming activity, and this high dispersion is related to the strong basicity of the BA surface. Strong basicity of BA and high dispersion of Co metal particles on BA are connected to high H2O reactivity to form H-2, probably at the interface between Co metal and BA. In addition, the Co/BA catalyst exhibited higher reusability through the coke combustion and the subsequent reduction treatment than the Co/Al2O3 catalyst. This is attributed to the suppression of the solid reaction between the oxidized Co and BA. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.