Uranyl fluoride

Uranyl fluoride (UO2F2), a salt of uranium, is an intermediate in the conversion of uranium hexafluoride UF6 to a uranium oxide or metal form and is a direct product of the reaction of UF6 with moisture in the air. It is very soluble in water. Uranyl fluoride also is hygroscopic and changes in color from brilliant orange to yellow after reacting with water. Uranyl fluoride is reported to be stable in air to 300 °C, above which slow decomposition to U3O8 occurs. When heated to decomposition, UO2F2 emits toxic fluorine fumes.

Uranyl fluoride
Uranyl fluoride
IUPAC name
Uranium fluoride oxide
Other names
Uranium oxyfluoride
ECHA InfoCard 100.033.529 Edit this at Wikidata
Molar mass 308.02 g/mol
Melting point Decomposes @ 300 °C
Boiling point Sublimes
Solubility in other solvents VS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

In accidental releases of UF6, UO2F2, as a solid particulate compound, may deposit on the ground. The overall chemical reaction of this event can be represented as:

UF6 + 2 H2O → UO2F2 + 4 HF.

These reactions can take place whether the uranium hexafluoride is a solid or a gas, but will take place almost instantaneously when the UF6 is in a gaseous state. The resulting hydrofluoric acid and the presence of additional water results in formation of solids (primarily hydrofluoric adducts of hydrated uranyl fluoride ().


Like any other uranium salt, it is radioactive, and precautions should be taken. It is also highly toxic. Uranyl fluoride is corrosive and harmful upon inhalation, ingestion, or skin absorption. Ingestion or inhalation may be fatal. Effects of exposure may be delayed.


  • Appendix A of the PEIS (DOE/EIS-0269) A literature review on the chemical and physical properties of uranyl fluoride, Myers, W.L. (Los Alamos National Lab., NM (USA) Illinois Univ. Urbana, IL (USA).