Thermal decomposition of cadmium formate, Cd(HCOO)2, was studied in dynamic helium and air atmosphere by means of simultaneous TGA, DTA and MS analysis. It was found that the cadmium formate decomposes at about 210°C to metallic cadmium and cadmium carbonate which next decomposes with formation of cadmium oxide. In helium cadmium melts, evaporates and the reaction residue consists of CdO and a small amount of elementary carbon formed in result of pyrolysis of formate groups. In air cadmium oxidizes and the final solid product of decomposition is CdO. The gaseous products of cadmium formate decomposition are: carbon dioxide, water, carbon monoxide, formaldehyde, methyl alcohol and methyl formate.