The in-flight modification of MoSi2 powders has been carried out by using an Ar-H2 induction plasma. Reactor pressure, powder feed rate and plate power level were taken as the experimental parameters to alter the thermal history of the injected powder particles. Metastable hexagonal structure of P-MoSi2 is the major phase observed in the induction plasma treated molybdenum disilicide powders, the stable phase of tetragonal structure of α-MoSi2 usually retains approximately 30 wt.%. Following the change in experimental condition and the deviation from stoichiometry in raw materials, low silicides, Mo5Si3 and Mo3Si, and free Si were observed. The formation of these phases are explained in terms of metastable eutectic reaction during rapid solidification processing. The relationship between the quantities of all these phases and the experimental conditions has been discussed.