The chemical analysis and the thermal decomposition of the complex are consistent with the formation of an intermediate, which is a mixture of ammonium carbonate and uranium trioxide, subsequently decomposing to ammonium uranate. The ammonium uranate decomposes to uranium trioxide which is finally reduced to U3O8. Thermal decomposition, infrared absorption spectra, and X-ray diffraction patterns are used to characterize the complex and the intermediate products of the thermal decomposition. Based on this data, the complex salt may be represented as (NH4)(2)[UO2(O-2)(C2O4)(H2O)(2)].H2O.