Hermetic thermal behavior of 3,4-diaminofurazan (DAF) was studied by DSC method with special high-pressure hermetic crucibles. The complete exothermic decomposition process of DAF can be provided. The extrapolated onset temperature, peak temperature, and enthalpy of decomposition at a heating rate of 10Kmin(-1) are 238.7 degrees C, 253.0 degrees C, and -1986Jg(-1), respectively. Self-accelerating decomposition temperature and critical temperature of thermal explosion of DAF are 232.3 and 253.1 degrees C, respectively. Specific heat capacity of DAF was determined with a micro DSC method and the molar heat capacity is 140.78Jmol(-1)K(-1) at 298.15K. Adiabatic time-to-explosion of DAF is about 90s. The thermal stability of DAF is good.