[C6F5Xe][AsF6] was prepared by metathesis from [C6F5Xe][(C6F5)2BF2]. The thermal stability of the melt (≤125 °C) is surprisingly high. The decomposition products reveal the ability of the cation to effect electrophilic pentafluorophenylation. [C6F5Xe][AsF6] crystallizes in the triclinic system, space group P1, with four molecules in the unit cell. Of these, two are symmetry independent with Xe−C distances of 2.079(6) and 2.082(5) A, Xe−F distances (cation−anion contacts) of 2.714(5) and 2.672(5) A, and C−Xe−F angles of 170.5(3) and 174.2(3)°, respectively. The relation between cations and anions is best described as an asymmetric hypervalent (3c−4e) bond. Temperature dependent 19F NMR measurements reveal the occurrence of separated ions in solution, with [C6F5Xe]+ coordinated by a basic solvent molecule. Minimum energy geometries and charge distributions were calculated for [C6F5Xe]+, [C6H5Xe]+, [C6F5]+, [C6H5]+, [CF3Xe]+, [CH3Xe]+, [C6F5Ng]+ (Ng = Kr, Ar, Ne, He), and [C6F5Xe][AsF6] at the ab initio RHF...