It is often difficult to compare results for heterogeneous reactions as the data reported in the literature are presented in. various ways. A common example of this difficulty is the reporting of oxygen adsorption rate constants in units such as 1 (g-catalyst)−1 s−1, 1 m−2 h−1, g m−2 h−1, g-mol m−2 h−1, etc. In this paper a number of studies involving oxygen interchange with vanadium pentoxide or vanadium pentoxide – potassium sulfate promoted catalysts are re-examined. Where possible, a first-order oxygen adsorption rate constant is evaluated from published data on rates of oxidation and rates of isotopic exchange, and expressed in units of 1 h−1 m−2 of catalyst surface. The rate constants so evaluated and compared as to catalyst composition, temperature, and activation energy show reasonable agreement, even though a variety of catalysts, processes, and techniques are involved.