Selenium hexafluoride is the inorganic compound with the formula SeF6. It is a colourless gas described as having a "repulsive" odor. It is not widely encountered and has no commercial applications. Like many compounds of selenium, SeF6 is hypervalent. The compound has octahedral molecular geometry with Se-F bond length 168.8 pm. SeF6 can be prepared from the elements or by the reaction of bromine trifluoride (BrF3) with selenium dioxide. The crude product is purified by sublimation.