Mechanical alloying (MA) synthesis of Ti3SiC2 from a stoichiometric elemental powder mixture of Ti, Si, and C was conducted by using a planetary mill with a specially designed MA jar, which enables the real-time measurement of temperature and gas pressure during the MA process. Sudden gas pressure and temperature rises were detected when the mixed powders were mechanically alloyed for a certain period, and consequently a large amount of Ti3SiC2 particles was synthesized. Using the Ti-Si-C system as an example, the present study confirmed the combustion reaction triggered by the ball-milling process for the first time.