Parent and mixed ligand complexes of cobalt and copper with antipyrine derivatives of 1,2-ethanediamine or piperazine and with 2-aminobenzothiazole (TAB) were synthesized and their thermal behaviour was investigated. The complexes contain N,N′-bis(4-antipyrylmethyl)-piperazine (BAMP) or N,N′-tetra(4-antipyrylmethyl)-1,2-diaminoethane (TAMEN) or/and TAB as ligand, and Cl−, ClO4− or SCN−. The complexes decompose with the evolution of heat. The decomposition route depends on the presence of ClO4−. If the ClO4− is not coordinated, it oxidizes the TAB and BAMP or TAMEN and the decomposition is explosive.