Al2O3/Ni nanocomposites were prepared by spark plasma sintering (SPS) using reaction sintering method and the mechanical properties of theobtained nanocomposites are reported. The starting materials of Al2O3–NiO solid solution were synthesized from aluminum sulfate and nickelsulfate. These Al2O3–NiO powders were changed into Al2O3 and Ni phases during sintering process. The obtained nanocomposites showed highrelative densities (>98%). SEM micrographs showed homogeneously dispersed Ni grains in the matrix. The 3-point strength and the fracturetoughness of the composites significantly improved from 450 MPa in the monolithic a-Al2O3 to 766 MPa in the 10 mol% (2.8 vol.%) Ninanocomposite and from 3.7 to 5.6 MPa m1/2 in 13 mol% (3.7 vol.%) Ni nanocomposite. On the other hand, Young’s modulus and Vickershardness of the nanocomposites were mostly same as those of the monolithic a-Al2O3.