Two new copper complexes, [Cu(phen) 2 FOX-7](phen)NO 3 ·4H 2 O and [Cu(phen) 2 FOX-7]Cl·3H 2 O (phen = 1,10-phenanthroline monohydrate; FOX-7 = 1,1-diamino-2,2-dinitroethylene) were synthesized and structurally characterized. Single crystal X-ray diffraction shows that Cu(II) in the two complexes has similar five-coordinate structure, including four nitrogens from two phen and one nitrogen from FOX-7 anion. Thermal decomposition behaviors of the two complexes were studied with differential scanning calorimetry and thermogravimetry/differential thermogravimetry methods. The apparent activation energies and pre-exponential constants of the main exothermic decomposition reaction for the two complexes are 208.1 and 183.1 kJ mol À1 , 10 22.99 and 10 19.19 s À1 , respectively. The self-accelerating decomposition temperature and critical temperature of thermal explosion for the two complexes are 152.64 and 162.17°C, 161.50 and 173.29°C, respectively.