[en] The UO₂(HCOO)₂x2HCONH₂ complex is synthesized. The compound prepared is investigated using the methods of chemical, X-ray phase and thermal analyses. IR spectroscopy and mass spectrometry. The complex is indexed in the rhombic crystal system with the following parameters: a=14.39; b=13.52; c=10.71 A. The process of thermal decomposition of formamide complex of dioxouranium (6) formate (poly-, isothermal, quasiisothermal conditions in the air, nitrogen and vacuum - 1x10^-2 torr) is investigated. It is established that the compound decomposes through two stages with a successive formation of UO₂(HCOO)₂xHCONH₂ and UO₃ (air) or U₃O₈ (nitrogen), or UOsub(2+x) (0.1< x<0.15) (vacuum) as solid products. Using the experimental data obtained the structure and the possible mechanism of thermolysis of the complex synthesized are discussed