Energies, electronic structures, and gas phase proton affinities of a series of gitonic protodiazonium and bisdiazonium dications as well as their parent diazonium ions were calculated using ab initio molecular orbital theory. On the basis of computed energetics, decomposition barriers of dications were estimated. NMR chemical shifts of the diazonium ions and protodiazonium dications were calculated using the IGLO method but only the former could be compared with experiment since protodiazonium dications may exist only in low equilibrium concentrations in the superacid media. The potential role of protodiazonium dications in superacid chemistry is discussed.