The catalytic effect of NiO nanoparticles on the thermal decomposition of double-base propellant composed of nitrocellulose (NC) and triethylene glycol dinitrate (TEGDN) has been investigated by thermogravimetry-mass spectrometry (TG-MS) coupling technique. It was shown that adding 2% of NiO nanoparticles to TEGDN/NC propellant can accelerate the thermal decomposition process after around 188 degrees C TG-MS analysis indicated that NiO nanoparticles have resulted in the increase in intensity (peak area) of m/z=27, 28, and 29 MS signals, but the decrease in the intensity of m/z=18, 30, 44 and 46 (peak 2) MS signals during the thermal decompsition. The catalytic mechanism was also discussed in this paper.