Simple and mixed compounds of the formulae Cu(4-Meim)(2), CuSal(4-Meim), CuSal(4-Meim)(2) and CuSalox(4-Meim)(2), where 4-Meim=4-methylimidazole, Sal=(OC6H4COO)(2-), Salox=(OC6H4CHNO)(2-) have been prepared. Thermal decomposition reactions have been established on the basis of thermal and X-ray analyses of these compounds. The pyrolysis proceeds in several (3-4) stages connected with the mass loss and exothermic effects. As a result of the last stage of decomposition CuO is formed.