In this study, MoSi 2 -TiB 2 nanocomposite was synthesized and characterized. For this purpose MoSi 2 matrix was firstly produced by mechanical alloying of molybdenum and silicon powders and the reaction mechanism and changes of grain size and lattice strain were investigated. The results showed that the formation of MoSi 2 takes place in a combustion mode but gradually propagates. The thermal stability of MoSi 2 was evaluated by annealing at temperatures between 700 to 1160 ?C. TiB 2 as a reinforcement was then synthesized by mechanical alloying of boron and titanium powders. The reaction mechanism was determined. The results showed that TiB 2 was produced with an explosion reaction after 12 hours of milling. The grain size and lattice strain and the thermal stability of TiB 2 were studied. The Miedema semi-empirical thermodynamic model was applied to both MoSi 2 and TiB 2 to compare amorphous and solid solution formation. Also, the grain growth kinetics of these phases was studied and the activation energies calculated. As the final goal of this research was fabrication of MoSi 2 -10% wt TiB 2 nanocomposite, two routes were used to synthesize this composite. In the first route, MoSi 2 was produced by milling and then Ti and B were added. The results showed that nanocomposite did not form even after 60 hours of milling. In the second route, Mo, Si, Ti and B powders with Stoichiometric ratio were milled. After 40 hours of milling, the desired nanocomposite was produced. The results of these two routes were compared and analyzed.