In this state-of-the-art quantum-chemical investigation we report structures, thermochemical stabilities, Born-Fajans-Haber cycles as well as vibrational data of heterodimeric and homodimeric radical cations of the series [F₂O₂]⁺, [F₂Cl₂]⁺, [Cl₂O₂]⁺, [F₄]⁺, and [Cl₄]⁺. The so far experimentally unknown species [F₄]⁺, [F₂O₂]⁺ and [F₂Cl₂]⁺ are predicted to be thermochemically stable and could be possible targets for gas-phase or matrix-isolation experiments. Furthermore, their stabilities as homodimeric [X₄]⁺ or heterodimeric [X₂Y₂]⁺ radical cation salts in the solid state have been estimated by Born-Fajans-Haber cycles.