6-((2H-tetrazol-5-yl)-amino)-1,2,4,5-tetrazin-3(2H)-one (TATzO) was synthesized and characterized by FT-IR, elemental analysis, ¹H NMR and ¹³C NMR and single crystal X-ray diffraction. The single crystal structure solution indicates that a hydrate forms (TATzO·H₂O) and it crystallizes in the orthorhombic Pnma space group with a density of 1.730 g·cm^-3 at 296 K. The thermal behavior and thermal decomposition kinetic of TATzO·H₂O were studied by differential scanning calorimetry (DSC) and thermogravimetry-derivative thermogravimetry (TG-DTG) methods. The thermal decomposition peak temperature is determined to be 230.46°C, indicating a similar thermal stability to cyclotrimethylenetrinitramine (RDX). The apparent activation energies (E) and pre-exponential constant (A) of the compound are 169.03 kJ·mol^-1 and 15.65 s^-1, respectively. The thermal ignition temperature (T_be) and the critical temperature of thermal explosion (T_bp) is 213.75℃ and 223.03℃，respectively. The enthalpy of formation was theoretically calculated by Gaussian 03, and the detonation velocity (D) and detonation pressure (p) were calculated by the Kamlet-Jacobs (K-J) equation. The obtained D and p are 7757m·s^-1 and 25.74 GPa, respectively. The impact sensitivity is larger than 24 J.