Steam co-gasification of iron catalyst-loaded biochar, which was produced by the pyrolysis of woody biomass and Indonesian Adaro subbituminous coal at 800 degrees C, was carried out in this study. The main purpose of this work was to examine the effectiveness of an iron catalyst loaded on biochar for hydrogen (H-2) evolution. It was shown that the H-2 evolution for a mixed sample of iron-loaded biochar (20 wt%) and Indonesian Adaro subbituminous coal increased by 20% compared with that for the coal sample with the same amount of iron catalyst and was approximately 1.5 that for the coal sample without the iron catalyst. This increase in the co-gasification H-2 evolution was explained by the chemical form and crystallite size of the iron catalyst. Copyright (C) 2016 John Wiley & Sons, Ltd.