The intriguing multi-ligand compound [Cu(IMI)4Cl]Cl (1) with the ligand imidazole (IMI) was synthesized and characterized by elemental analysis and FT-IR spectroscopy. The crystal structure was determined by X-ray single crystal diffraction and the crystallographic data showed that the compound belongs to the monoclinic P21/n space group [α = 8.847(2) Å, b = 13.210(3) Å, c = 13.870(3) Å, and β = 90.164(3)°]. Furthermore, the CuII ion is five-coordinated by four nitrogen atoms from four imidazole ligands and a chlorine atom. The thermal decomposition mechanism was determined based on differential scanning calorimetry (DSC) and thermogravimetric (TG-DTG) analysis. The non-isothermal kinetics parameters were calculated by the Kissinger's method and Ozawa's method, respectively. The energy of combustion, enthalpy of formation, critical temperature of thermal explosion, entropy of activation (ΔS≠), enthalpy of activation (ΔH≠), and free energy of activation (ΔG≠) were measured and calculated.