Crystals of difluorochlorine(III)hexafluoroarsenate(V), ClF2AsF6, are monoclinic, space group A2/a, a = 10.676(9), b = 7.673(7), c = 8.064(7) Å, β = 113.40(5)°. The structure was refined by three dimensional least squares methods to R = 0.045 for 185 independent observed reflections. The chlorine atom has two nearest fluorine neighbors at 1.541(14) Å, with a F—Cl—F angle of 103.17(0.70)°, and two longer fluorine bonds at 2.339(14) Å. All five atoms lie in a plane. The arsenic atom is octahedrally coordinated to six fluorine atoms and is connected to two ClF2+ groups via trans fluorine bridges.