This study dealt with the characterization of MoSi2 based composites containing three types of additive materials such as SiC, NbSi2 and ZrO2 particles have been investigated, based on the detailed examination of their microstructures and fracture surfaces. The effects of reinforcing materials on the high temperature strength of MoSi2 based composites have been also examined. MoSi2 based composites were fabricated by the hot press process under the vacuum atmosphere. The volume fraction of reinforcing materials in the composite system was fixed as 20 %. The microstructures and the mechanical properties of MoSi2 based composites were investigated by means of SEM, EDS, XRD and three point bending test.