A one-chamber solid oxide fuel cell (working in a methane-air mixture) with yttria-stabilized zirconia (YSZ) electrolyte was modified by adding oxide to the anode (Pt) and cathode (Au). It was determined that the addition of MnO2 to both electrodes significantly improved the cell discharge characteristics. The short-circuit current density of a cell using 15 wt % MnO2 added to the Pt and 20 wt % MnO2 added to the Au was about 50 times larger than that of a cell using Pt and Au electrodes. Moreover, the cell performance was enhanced further when 1 wt % MnO2 was doped into the YSZ electrolyte. Microstructural observations of the YSZ electrolyte/electrodes interfaces indicated that both the electrode porosity and the contact areas between electrodes and YSZ electrolyte increased markedly for the MnO2-containing Pt and Au electrodes. In addition, the electrocatalytical property of MnO2 added in the electrodes may also contribute to the improved cell performance.