The effect of additional phases, mainly metal-boride and metal-nitrides, on the microstructure and some mechanical properties of γ-TiAI(55/45)-based titanium aluminides have been investigated. The considerable changes in the microstructure of γ-TiAl-based titanium aluminides were achieved by the addition of metal-boride and nitrides into γ-TiA1 titanium aluminides. Fine and duplex microstructures of γ-TiAl matrix, in which the lamellar phase was dispersed in the equi-axed γ-TiAI matrix grains, were observed by SEM and TEM. After reaction sintering, formation of Ti₂N and Ti₂AIN phases and simultaniously Cr, Nb and Zr solid solution into γ-TiAl titanium aluminides were confirmed. Especially, NbN addition inhibited the grain growth of matrix and resulted in the increase in bending strength and hardness at room temperature.