Factors responsible for determining selectivity in the reactions of small hydrocarbons over supported metal catalysis are investigated. A variety of techniques are used to probe the interactions of hydrocarbons with the catalyst surface, including microcalorimetry, temperature-programmed reaction spectrometry, isotopic tracer studies, infrared and laser Raman spectroscopies, Moessbauer spectroscopy, magnetic susceptibility, nuclear magnetic resonance, electron microscopy, and reaction kinetics. The activation of small hydrocarbons is one of the main areas of active research in catalysis. It has application to liquid fuels productions and many chemical processes. A knowledge of the factors influencing selectivity is necessary to permit design of process control strategies.