A Ni-samaria-doped ceria (SDC) anode is employed for direct electrochemical oxidation of methane in a solid oxide fuel cell (SOFC) with yttria-stabilized zirconia (YSZ) as electrolyte to seek insights into the properties and electrocatalytic activity of the anode. Compared with Ni-YSZ, the Ni-SDC anode exhibits higher open-circuit voltages (OCVs) and a lower degree of polarization. The anodic polarization of Ni-SDC is shown to result from the effect of concentration polarization. The effect of nickel content in Ni-SDC on the performance and microstructure of the anode are studied. It is found that the anodic polarization and electrocatalytic activity strongly depend on the Ni content in the anode, and optimum results are achieved with 60 wt.% Ni. The good performance of this Ni-SDC anode appears to be due to its microstructure. In addition, the anode is stable in a methane environment. (C) 2003 Elsevier Science B.V. All rights reserved.