This report presents the preparation and characterization of a xenon-containing cationic radical species, XeOO⁺. The XeOO⁺ cation was produced either by co-deposition of the reactive species generated by laser ablation of different transition metals with dioxygen and xenon mixtures in excess argon or by condensation of high-frequency discharged O₂/Xe/Ar mixtures at 12 K and is identified by infrared absorptions. High-level quantum chemical calculations indicate that XeOO⁺ has a bent structure with direct xenon−oxygen dative bonding, and the doublet ground state is much more stable than the Xe + O₂⁺ reactants.