A new complex of magnesium with tetrazole-l-acetic acid （tza） has been synthe- sized and characterized by elemental analysis and FT-IR spectrum. Single-crystal X-ray diffraction analysis determined the molecular formula as Mg（tza）2（H20）4. The crystal belongs to the triclinic system with Pi space group, and a = 6.133（2）, b = 6.488（2）, c = 10.0127（7） A, a = 77.282（10）, fl = 91.558（1）, ）, = 76.002（8）°, Y = 349.0（2）A3, Z = 1, C6HI4MgNsOs, Mr = 350.56, Dc = 1.668 g.cm-3, F（000） = 182,μ = 0.189, S = 1.000, the final R = 0.0294 and wR = 0.0785 for 1128 observed reflections with I 〉 20-（I）. In this molecule, the tza ion exhibits an infrequent monodentate coordination mode. The magnesium center is hexa-coordinated to a slightly distorted octahedral configuration by six oxygen atoms from two tza ligands and four coordinated water molecules. DSC and TG-DTG analyses were applied to assess the thermal decomposition behavior. The kinetic parameters of the exothermal peak were calculated by non-isothermal reaction kinetics. The values of critical temperature of thermal explosion, △S≠, △H≠ and △G^≠, were obtained as 596 K, -42.25 J mo1^-1 K^-1, 296.43 kJ mol^-1 and 323.53 kJ mol1, respectively.
