The oxidative dehydrogenation of ethane to ethylene has been investigated in the 550-650-degrees-C temperature range over Li/Bi/CaO catalysts. This class of catalysts are very selective to ethylene. The Li/Bi/CaO catalyst gives a rather high activity and excellent selectivity to ethylene. Experiments indicate that the existence of bismuth and the coordinative action of lithium and bismuth in Li/Bi/CaO catalyst are probably the causes of the increased activity and selectivity, respectively. The characteristics of the catalysts was studied by X-ray diffraction, X-ray photoelectron spectroscopy and thermal analyses. The differences in catalytic activities observed between Li/Bi/CaO and several other CaO based oxide catalysts can be explained by the results of these characterization studies.