A model biogas consisting of 60% CH4 and 40% CO2 was reformed by steam at 101.3 kPa pressure over a metal-foam-coated 1.31 wt% [Pd(7)-Rh(1)]/(CeZrO2-Al2O3) catalyst in a tubular reactor at GHSV 10,000 h (1). Reactant conversion, product selectivity, process thermal efficiency and coke formation were evaluated by varying S/C ratio as 1.00-2.00 in the temperature range of 923-1123 K. CO2 in the biogas as well as steam reacted to reform CH4, whose conversion was significantly contributed by dry reforming at 973 K for S/C ratio of 1.25 or 1.50. Dry reforming contribution was attenuated by steam reforming as S/C ratio or reaction temperature increased. H-2/CO selectivity increased and CO/(CO + CO2) selectivity decreased as S/C ratio increased; the former decreased and the latter increased as reaction temperature increased. CO2 conversion was not so high due to the competition of dry reforming with WGS/RWGS. Process thermal efficiency and coke formation were dependent upon S/C ratio and reaction temperature in a rather complicated manner. According to the performance guidelines defined in this study, S/C = 1.50 and 1023 K were selected as optimum steam-biogas reforming condition, at which the catalytic stability was maintained for 200 h onstream period at the increased GHSV of 20,000 h (1). (C) 2014 Elsevier Ltd. All rights reserved.