Al2O3-MoSi2 composites were prepared by reactive hot pressing using molybdenum, aluminum, and mullite powders as precursors. The Gibbs free energy was highly negative for the composite-forming reaction, which indicated that the products were stable relative to the reactants. After the reaction, the composites had high relative density, similar to96%. Based on the composite-forming reaction, the composites should have contained 18 vol% MoSi2 in an Al2O3 matrix. Scanning electron microscopy revealed that the MoSi2 inclusions were elongated, with an average thickness of similar to5 mum and inclusion lengths that ranged from 5 to 50 mum. Average composite strength was 467 MPa, and toughness was 3.7 MPa(.)m(1/2).