One- and two-chamber solid oxide fuel cells (SOFCs) fed by an air-methane mixture (AMM) were studied at 550-700 degreesC. (Y2O3)(0.04)(Sc2O7)(0.06)(ZrO2)(0.9) was used as a solid electrolyte, ceria-doped Ni-YSZ-cermet (CNC) and SrO-doped LaMnO3 (LSM) were used as electrodes. In the experiments with the two-chamber cell, it was stated that the LSM-electrode did not catalyse methane partial oxidation and its potential was close to the potential of free oxygen mixed with methane and nitrogen. The CNC-electrode was a good catalyst for methane partial oxidation and its potential was close to the potential of the mixture formed in methane partial oxidation process. In the one-chamber cell, the current density was about 15 mA/cm(2) at the terminal voltage 500 mV within an interval of 550-650 degreesC. (C) 2000 Elsevier Science B.V. All rights reserved.