The electrical conductivity and mechanical properties of Sc2O3-ZrO2(ScSZ) prepared by a sol-gel method were investigated. To improve mechanical strength, the composite materials of ScSZ and Al2O3 were investigated. A flat-plate type SOFC, with 11 mol% ScSZ used as an electrolyte, was fabricated. In a cell test a maximum power density of 1.61 W/cm(2) was obtained at 1273 K.