A Ni based catalyst supported on a cordierite monolithic substrate was applied to the autothermal reforming (ATR) of biogas to produce hydrogen. When the feed rates of oxygen and steam were constant, the Steam/CH(4) (S/CH(4)) and O(2)/CH(4) ratios changed because of an increase or decrease in the methane concentration of the biogas. The concentration of methane in the biogas fluctuates roughly between 35% and 65% according to factors such as the properties or amount of the waste. Therefore, the effect of S/CH4 and O(2)/CH(4) ratios on catalyst durability was confirmed by using actual biogas, which was produced by anaerobic fermentation of biomass at the biogasification bench-scale plant in Kyoto. Reforming reactions were carried out at ratios of S/CH(4)=0-4, O(2)/CH(4)=0.5 and at S/CH(4) = 2, O(2)/CH(4) = 0.6. The S/CH(4) range of 0-2.0 and the O(2)/CH(4) range of 0.5-0.6 had no effect on the catalyst durability and a S/CH(4) ratio of more than 3.0 led to decreased catalytic performance. Actual biogas contains minor components such as hydrogen sulfide, siloxanes and other organic materials. It was difficult to completely remove these compounds. The influence of these compounds was investigated during an experiment, which lasted for 250 h using actual biogas. We confirmed that the residual organic compounds had no effect on the catalytic activity, and that a stable performance was obtained under suitable conditions for the feed rate of steam and oxygen. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.