The contributions of our group on proton transfer processes in hydrogen bonded radical cations are reviewed.  First, the adequacy of different levels of theory for studying these systems is discussed.  In particular, the behavior of density functional approaches is compared to traditional post-Hartree-Fock methods.  It is shown that B3LYP method appears to be a cost-effective alternative for studying proton transfer reactions, whenever three electron hemibond structures are not competitive.  Second, a chemical insight on the inter and intramolecular proton transfer processes for some systems is provided.  For the intermolecular cases, ionization of the proton donor monomer increases its acidity and thus, the proton transfer reaction occurs easily or even spontaneously.  For intramolecular H-bonded systems, ionization modifies both the acidity and basicity of the involved groups.  In these cases the proton transfer reaction occurs more or less easily depending on the nature of the ionized electronic state.  Finally, it is shown that solvent molecules catalyze radical cation isomerizations.