The geometry, electronic structure and thermochemical properties of transition metal carbohydrazide perchlorates MCP [M = Co(II), Ni(II), Zn(II), Cd(II)] are investigated via density functional theory (DFT). The results show that the Heyd-Scuseria-Ernzerhof (HSE) functional yields the most accurate geometry. Detailed NBO analyses indicate that the metal-ligand interactions of CoCP and NiCP are covalent, whereas those of ZnCP and CdCP are ionic in nature. The mechanism of detonation initiation in covalent and ionic complexes is entirely different. There is a relationship between the energy gap and impact sensitivity. The thermochemical properties show that the formations of these complexes are exothermic; moreover, CoCP and NiCP are easier to decompose than ZnCP. (C) 2010 Elsevier B.V. All rights reserved.