Alumina (Al2O3) and alumina-yttria stabilized zirconia (YSZ) composites containing 3 and 5 mass% ceria (CeO2) were prepared by spark plasma sintering (SPS) at temperatures of 1350-1400 °C for 300 s under a pressure of 40 MPa. Densification, microstructure and mechanical properties of the Al2O3 based composites were investigated. Fully dense composites with a relative density of approximately 99% were obtained. The grain growth of alumina was inhibited significantly by the addition of 10 vol% zirconia, and formation of elongated CeAl 11O18 grains was observed in the ceria containing composites sintered at 1400 °C. Al2O3-YSZ composites without CeO2 had higher hardness than monolithic Al2O 3 sintered body and the hardness of Al2O3-YSZ composites decreased from 20.3 GPa to 18.5 GPa when the content of ZrO 2 increased from 10 to 30 vol%. The fracture toughness of Al 2O3 increased from 2.8 MPa m1/2 to 5.6 MPa m1/2 with the addition of 10 vol% YSZ, and further addition resulted in higher fracture toughness values. The highest value of fracture toughness, 6.2 MPa m1/2, was achieved with the addition of 30 vol% YSZ. © 2011 Elsevier Ltd and Techna Group S.r.l.