Anode-supported cells made of conventional materials were tested in single-chamber conditions under various CH4/air gas mixtures. Methane-to-oxygen ratio (R-MIX) and nominal temperature between 600 and 800 degrees C both affect the performance of the cell. At a flow rate of 350 sccm, maximum values of power density (260 mW cm(-2)) and cell voltage (1.05 V) were obtained for R-MIX = 2 at 800 degrees C. However, short term ageing experiments show that the stability of the cells depends on R-MIX as well as the flow of current. Scanning electron micrographs (SEM) reveal some important changes in anode microstructure close to the fuel inlet that may be, assign to the volatilization of the nickel contained in the Ni-YSZ cermet. (c) 2005 Elsevier B.V. All rights reserved.