High nitrogen content energetic compounds 3,6-diguanidino-1,2,4,5-tetrazine [(DGTz)(H2O)(2)] and its diperchlorate [(DGTz)(ClO4)(2)] were prepared and characterized by elemental analysis and Fourier transform infrared (FT-IR) spectroscopy. Their crystal structures were determined by applying X-ray single crystal diffraction. The hydrogen atoms in the 3- and 6-sites of the tetrazine heterocycle have been disubstituted by guanidine groups for (DGTz)(H2O)(2), and two crystal water molecules were present. In the (DGTz)(ClO4)(2) molecule, two ClO4- and one DGTz(2+) groups were bonded together by electrostatic attraction and hydrogen bonds. The thermal decomposition process of the two compounds was investigated through differential scanning calorimetry (DSC) and thermogravimetric/differential analysis (TG-DTG). The results of the decomposition are nearly gaseous products. The kinetic parameters of the exothermic process were calculated by using Kissinger's and Ozawa-Doyle's methods.