The operating properties of solid oxide fuel cells using Ni/scandia-stabilized zirconia (Ni-ScSZ) anodes under internal reforming conditions are investigated. A single-cell achieved a maximum power density of 0.64W cm(-2) at 900degreesC in 97%CH4/3%H2O mixture fuel. The cell voltage during the power generation at 0.5 A cm(-2) is stable in 97%CH4/3%H2O mixture fuel at 900degreesC for at least 150h. By contrast, degradation of anode performance and carbon deposition are found at 800 degreesC under the same conditions. These results suggest that carbon deposition is hindered more effectively at higher temperature under operation at high current density. (C) 2004 Elsevier B.V. All rights reserved.