Combustion synthesis reactions were investigated in the Mo-Si-Al ternary system along the MoSi-MoAl tie line. The experimental data show that addition of Al helps the exothermicity of the reaction, presumably with the help of a transient eutectic liquid in the Al-Si system. XRD patterns show that, with increasing Al content, the original C11 structure of MoSi transforms into its high temperature polymorph hexagonal C40 structure. No trace of free Al was observed in the XRD patterns. Therefore, Al dissolves into MoSi structure substantially. SEM micrograph shows inhomogeneity in the microstructure.