The Co/Mg/Al catalysts were prepared from the hydrotalcite-like compounds containing Co, Mg and Al, and applied to the steam gasification of biomass. It is found that the Co/Mg/Al (10/40/50) catalyst exhibited much higher activity and resistance to coke deposition than Co/alpha-Al2O3, Co/Al, Co/Mg and Ni/Mg/Al (9/66/25) catalysts. The catalyst characterization using BET, TPR, TPO, XRD, H-2 adsorption, and TEM indicates that the Co/Mg/Al (10/40/50) catalyst after the reduction has a nanocomposite structure of Co metal particles (similar to 14 nm) and oxide particles (similar to 16 nm) of MgAl2O4-based solid solution. On the other hand, according to the catalyst characterization after the catalytic use and regeneration, the structural change of MgAl2O4-based solid solution to MgO-based solid solution can be a cause of the decrease of the catalytic activity. (C) 2013 Elsevier B.V. All rights reserved.