Imidazole-4,5-dicarboxylic acid (H(2)imdc) is a useful model for biomimetic complexes among the polycarboxylate ligands, characterized by the presence of two or more carboxyl groups in different orientations. In this study, Cu(II) and Ni(II) complexes with (Himdc)(-) ligand were synthesized. The precipitated Cu(Himdc)(2)(H2O)(2) and Ni(Himdc)(2)(H2O)(2) complexes were characterized and their stability was studied by thermoanalytical techniques coupled to mass spectrometry, to prove their decomposition mechanism by evolved gas analysis (EGA-MS). (C) 2013 Elsevier B.V. All rights reserved.