The recent observations of resonant tunneling through unoccupied orbitals of molecular species imbedded in metal-insulator-metal tunnel junctions are discussed in terms of transient reduction of the molecular species. Electrochemical reduction potentials for the solution phase molecular systems are compared to the orbital-mediated tunneling spectroscopy (OMTS) data, and a strong correlation is observed. A simple model is proposed that accounts for this correlation. This model also explains previous observations of spontaneous and permanent reduction of certain compounds in the tunnel junction environment. The model should be equally applicable to resonant tunneling and to spontaneous reduction observed in the scanning tunneling microscope. Based on the view presented here, orbital-mediated tunneling spectroscopy is a new method for providing reduction potentials and affinity levels in adlayers and thin solid films.