Abstract: With the aim of studying the effect of Si on Mechanical Alloying (MA) process of TiAl (γ) intermetallic compound, two compositional powder blends of Ti-50Al(at%) and Ti-48Al-2.4Si(at%) were mechanically alloyed in a planetary ball mill. The structural evaluation in these powders was done by X-Ray Diffraction (XRD) technique and Scanning Electron Microscopy (SEM). It was found that elemental powders were progressively transformed into nanocrystalline Ti solid solution and amorphous phases during MA process. The time required for Ti solid solution or amorphous phase formation was longer in Si containing powders. While annealing of the mechanically alloyed Ti-50Al powders at 900°C for 10 min leads to the nanocrystalline phase of TiAl(γ), nanocrystalline phases of mainly TiAl(γ) together with some silicides and Ti3Al(α2) phase were formed in Si containing powders. Annealing at higher temperature of 1150°C leads unstable silicides to be transformed into more stable ζ-Ti5Si3 phase.