Single-chamber cells of two different types have been operated between 700 and 800 degreesC in various methane-air mixtures. These cells are made mostly of conventional materials for solid oxide fuel cells (SOFCs), strontium-doped lanthanum manganite, yttria-stabilized zirconia (YSZ), and Ni-YSZ cermet. One type is electrolyte-supported, while the other represents a state-of-the-art fabrication for anode-supported cells. The anode-supported cells operate in a narrower range of methane-air ratios, but offer remarkable maximum specific powers, 360 and 285 mW/cm(2) at 800 and 700 degreesC, respectively. Some theoretical considerations about the actual operation of these cells are also provided. (C) 2004 The Electrochemical Society.