Single chamber solid oxide fuel cells (SC-SOFCs) based on the system Sm0.5Sr0.5CoO3-delta/Ce0.9Gd0.1O1.95/Ni-Ce0.8Gd0.2O1.90 were investigated. Pt-meshes that were embedded in both electrodes were used as current collectors in order to achieve low overpotentials. The cells generated 271 mW/cm(2) at 500 degrees C and 468 mW/cm(2) at 600 degrees C on a gas mixture of methane and air (CH4/O-2 = 1.6) with a total flow of 1500 ml/min. The air flow was varied (260, 780, 1120, and 1340 ml/min) while the flow of methane was kept at 380 ml/min. It was found that the open circuit voltage (OCV) and the maximum power density (P-max) were strongly dependent on the airflow and the operating temperature. The influences of Palladium-addition to the anode as well as Co-doping of the electrolyte on the OCV and P-max have been studied and compared to an unmodified cell. Pd-containing anodes allow for higher power outputs at low airflow. The presence of Co in the electrolyte raises the OCV but decreases the maximum power density. (c) 2005 Elsevier B.V. All rights reserved.