The nitrate complexes of transition metals with 1,2-diimidazoloethane (DIE) of the general formula M(DIE)(NO3)(2), where M = Co(II), Cu(II), Zn(II), and Cd(II), were synthesized. The compositions of metal complexes and ligand were investigated by elemental analysis in order to ensure their purity and the structure elucidations were based on conductivity measurements, room temperature magnetic moment studies, proton NMR, and electronic and IR spectra. The thermal behavior of these complexes possessing distorted tetrahedral geometry and their ligand was studied by means of thermoanalytical techniques in static air atmosphere in order to determine their mode of decomposition and thermal stability. All these complexes and ligand show 2-step weight loss upon heating to 740 degrees C, with simultaneous loss of inorganic and organic fragments exhibiting almost the same mode of decomposition pattern. The residue after heating above 640 degrees C corresponded to metal oxide. There was no residue in the case of ligand. The composition of intermediates and end products formed during degradation was confirmed by microanalysis and IR spectroscopy. It follows from the results that the thermal stability of the complexes increases in the following sequence: Co(II) < Cu(II) < Zn(II) < Cd(II)