The power balances of gas cells having atomized hydrogen from pure hydrogen alone, an argon-hydrogen mixture alone, or pure hydrogen or an argon-hydrogen mixture with vaporized potassium, rubidium, Cesium, strontium, sodium, or magnesium were measured by integrating the total light output corrected for spectrometer system response and energy over the visible range as the input power was varied. The light emitted for power supplied to the glow discharge increased by over two orders of magnitude depending on the presence of less than 1% partial pressure of certain of the alkali or alkaline earth metals in hydrogen gas or argon-hydrogen gas mixtures. Whereas, other chemically similar metals had no effect on the plasma. The metal vapor enhancement of the emission was dramatically greater with an argon-hydrogen mixture versus pure hydrogen, and a 97% argon and 3% hydrogen mixture had greater emission than either gas alone. Only those atoms or ions which ionize at integer multiples of the potential energy of atomic hydrogen, potassium, cesium, Rb+, strontium, and Ar+ caused an anomalous increase in emission; whereas, no anomalous behavior was observed in the case of Mg(m) and Na(m) which do not provide a reaction with a net enthalpy of a multiple of the potential energy of atomic hydrogen. The light intensity versus power input of a mixture of these metals with hydrogen, argon, or argon-hydrogen gas was the same as that of the corresponding gas alone. At an input power to the glow discharge of 10 W, the optically measured light output power of a mixture of strontium, cesium, potassium, or rubidium with 97% argon and 3% hydrogen was 750, 70, 16, and 13 muW/cm(2), respectively. Whereas, the optically measured light output power of the argon-hydrogen mixture (97/3%) alone or with sodium or magnesium was about 11 muW/cm(2), and the result for hydrogen or argon alone was 1.5 muW/cm(2). A temperature dependence of some of the anomalous plasmas was determined corresponding to the metal's partial pressure dependence on temperature. These studies provide useful parameters for the optimization of the catalytic reaction of atomic hydrogen for power generation. An excess thermal balance of 42 W was measured for the 97% argon and 3% hydrogen mixture versus argon plasma alone. (C) 2002 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.