The thermal properties of 2,4,6-trinitrotoluene (TNT), TNT/MgH2, and TNT/Mg(BH4)(2) were investigated by differential scanning calorimetry (DSC) and accelerating rate calorimetry (ARC). The results show that addition of MgH2 or Mg(BH4)(2) to TNT has a great effect on the DSC decomposition process. The exothermic decomposition peak of TNT disappeared and was replaced by a slow exothermic trend in the curves of both TNT/MgH2 and TNT/Mg(BH4)(2). The kinetic triplet of TNT formulations were calculated by ARC data. The results show that TNT/MgH2 and TNT/Mg(BH4)(2) have lower onset temperatures, apparent activation energies (E) and frequency factors (A) than neat TNT. A change of the TNT decomposition mechanism is also discussed.