X-irradiation of Ph₃AsF₂ single crystals produces a radical exhibiting hyperfine coupling with one ⁷⁵As nucleus and two ¹⁹F nuclei. The three hyperfine tensors are determined and show that the unpaired electron is delocalized in 4s (17%) and 4p (55%) arsenic orbitals and in a 2p (~12%) orbital of each fluorine atom. The ESR parameters are consistent with either Ph₂AsF₂ or Ph₃AsF₂^- but theoretical estimates of the geometry of these two species together with the experimental angle of 135° between the principal axes of the two fluorine hyperfine coupling tensors are more in accord with the structure Ph₃AsF₂^-.