1,4-Dihydro-5H-(dinitromethylene)-tetrazole ammonium salt ((NH4)2DNMT), a high nitrogen energetic compound, was synthesized and structurally characterized by single-crystal X-ray diffraction. The thermal behavior of (NH4)2DNMT was studied with DSC and TG-DTG methods. The kinetic equation of the thermal decomposition reaction is: da/dT=1013.17/3 beta(1-a)-2 exp(-1.388x105/RT). The critical temperature of thermal explosion is 182.7?degrees C. The specific heat capacity of (NH4)2DNMT was determined and the molar heat capacity is 301 J?mol-1?K-1 at 298.15 K. The adiabatic time-to-explosion of (NH4)2DNMT was calculated to be 277 s. The detonation velocity and detonation pressure were also estimated. All results showed that (NH4)2DNMT presents good performance.