We investigated the performance of Ni + MnOx/Al2O3 catalysts in the steam reforming of tar from the pyrolysis of cedar wood. Performance of Ni + MnOx/Al2O3 catalyst with optimum composition was much higher than those of the corresponding monometallic Ni and MnOx catalysts. This tendency is also supported by the activity test in the steam reforming of toluene as a model compound of tar. Based on the catalyst characterization results, the surface of Ni metal particles was partially covered with MnOx, and the interaction between Ni metal and MnOx can play an important role on the enhancement of the catalytic activity and the suppression of coke deposition in the steam reforming of tar. Excess MnOx addition decreased the catalytic activity by decreasing the number of the surface Ni atoms. (C) 2011 Elsevier Ltd. All rights reserved.