The radical cations generated from three NADH model compounds were investigated with particular emphasis on the possible formation of tautomeric enol radical cations. To a small extent, hydrogen transfer occurs upon ionization of all three compounds in argon matrixes. In the bicyclic seven-membered ring derivative enolization continues in athermal reaction at 12 K (with highly dispersive kinetics), or upon visible irradiation. These processes are not observed in methylcyclohexane glasses at 77 K, which indicates that a cage effect is preventing the attainment of a reactive conformation in this medium. The assignment of electronic spectra of the primary (keto) cations and of their tautomeric (enol) forms is supported by CASSCF/CASPT2 and TD-B3LYP calculations.