Xenon octafluoride is a chemical compound of xenon and fluorine with the chemical formula XeF8.

[1][2] XeF8 is reported to be unstable even under pressures reaching 200 GPa.

[3] The compound was initially predicted in 1933 by Linus Pauling—among other noble gas compounds but which, unlike other xenon fluorides, could probably never be synthesized.

[4][5] This appears to be due to the steric hindrance of the fluorine atoms around the xenon atom.

[6] The formation of xenon octafluoride has been calculated to be endothermic:[7]