The thermal decomposition of Co(II), Ni(II) and Cu(II) complexes has been studied using thermogravimetry (TG) and differential TG (DTG). The complexes have been characterized by IR spectroscopy. The results reveal that the decomposition of these complexes is accompanied by the formation of metal acetate as an intermediate fragments. On the basis of the applicability of a non-isothermal kinetic equations, it was demonstrated that the stability of the complexes follows the order Co(II) > Cu(II) > Ni(II). These stably correspond to the strength of chelation between the metal ions and the primary and secondary ligands. A possible mechanism of the thermal decomposition of the complexes is suggested. (C) 2003 Elsevier B.V. All rights reserved.