In this work, methods for the synthesis of complex compounds of Ni (II) oxalate with Ca, Cu (II), Co acetates were studied and reactions were carried out. In order to study the composition of the obtained complex compounds, elemental analysis was carried out and the theoretical results were compared. Thermal analysis was carried out to determine the coordination bonds formed in the composition of complex compounds. By thermal analysis methods - thermogravimetric analysis (TGA) and differential thermal analysis (DTA), the stability of the complexes, stepwise decomposition processes, and thermal effects were determined. As a result, it was established that Ni (II) complexes change in various temperature ranges in the presence of oxalate and acetate ligands, and as a result of their decomposition, oxide products are formed.