Thermal behaviors of three mixed-ligand complexes, [Ni(PMBP-PNH)(Py)3], [Ni(PMBP-PNH)Py] and [Cu(PMBP-PNH)Py] (PMBP-PNH = N-(1-phenyl-3-methyl-4-benzylidene-5-pyrazolone)p-nitrobezoylhydrazide; Py = pyridine), were studied by TG and DTG in dynamic air atmosphere. The complexes show the loss of pyridine molecule which is followed by the decomposition of the PMBP-PNH anion and give respective metal oxides as residues. Meanwhile, the Ozawa-Flynn-Wall model-free analyses and multivariate non-linear regression were applied to perform single and overall steps optimization. Kinetic parameters were given and the most probable mechanism functions were suggested in this study. (c) 2004 Elsevier B.V. All rights reserved.