Power generation characteristics and internal reforming characteristics of anode-supported solid oxide fuel cells (SOFCs) with a thin scandia-alumina-stabilized zirconia (SASZ) electrolyte and a lanthanum nickel oxide (LNF) cathode were investigated under the condition of low steam/methane ratios or steam/carbon ratios (S/C). Exhaust gas flow rate of H-2 and CO increased and the rate of CH4 decreased with increasing current density at S/C = 0.5. The ratio of the gas flow rate increase of H-2 to CO was approximately constant (H-2/CO = 2), and no apparent carbon formation on the surface of anode was observed. We calculated the exchange current densities from results of anodic overpotential measurements at S/C = 0.5 and 2.0. The exchange current density at S/C = 0.5 differed from the exchange current density at S/C = 2.0 which was similar to the exchange current density in case of using H-2 fuel. These results suggest that the electrochemical reaction in anode at S/C = 0.5 involves the partial oxidation of CH4. (C) 2004 The Electrochemical Society.