Three sets of heat production and “ash” identification data are presented. An exothermic reaction is reported wherein the electrons of hydrogen and deuterium atoms are stimulated to relax to quantized potential energy levels below that of the “ground state” via electrochemical reactants K+ and K+; Pd2+ and Li+; or Pd and O2 of redox energy resonant with the energy hole that stimulates this transition. Calorimetry of pulsed current and continuous electrolysis of aqueous potassium carbonate (K+/K+ electrocatalytic couple) at a nickel cathode were performed. The excess output power of 41 W exceeded by a factor >8 the total input power given by the product of the electrolysis voltage and current. The product of the exothermic reaction is atoms having electrons of energy below the ground state, which are predicted to form molecules. The predicted molecules were identified by their lack of reactivity with oxygen, by separation from molecular deuterium by cryofiltration, and by mass spectroscopic analysis.