The electrical, mechanical and thermal properties of the 8 mol% yttria-stabilized zirconia (8YSZ) and alumina composites have been examined as a function of the alumina content. The temperature dependence of bending strength of 8YSZ showed a minimum at 500-degrees-C. The strength at 1000-degrees-C was 250 MPa, almost comparable to that at room temperature (RT). The strength of the composites increased with increasing alumina content up to 20 wt%. The composite with 20 wt% Al2O3 (20A8YSZ) showed a 3-point bending strength of 320 MPa and an excellent thermal shock resistance. The thermal conductivity of the composite increased and the thermal expansion coefficient decreased with increasing alumina content. The electrical conductivity of the composites at 1000-degrees-C increased slightly with increasing Al2O3 content up to 1 wt% and decreased monotonically with alumina content. The conductivity of 20A8YSZ was 1.0 x 10(-1) S/cm at 1000-degrees-C.