Oxidized diamond demonstrated excellent support for the dehydrogenation of light alkanes to alkenes in the presence of CO2. Oxidized diamond-supported Cr2O3 and V2O5 catalysts exhibited comparatively higher catalytic activities in the dehydrogenation of lower alkanes in the presence of CO2. In the dehydrogenation of propane, the oxidized diamond-supported Cr2O3 and V2O5 catalysts in the presence of CO2 afforded nearly twofold higher activities than that in the absence of CO2. The activity of the oxidized diamond-supported V2O5 catalyst in the dehydrogenation of propane increased with increasing reaction temperatures. Furthermore, in the dehydrogenation of n-butane and iso-butane, a promoting effect of CO2 on butane conversion and butenes yields was observed over the oxidized diannond-supported Cr2O3 and V2O5 catalysts, though the promotion effect was small.UV-Vis analyses of the fresh and the reacted catalysts in the presence and absence of CO2 revealed that CO2 kept the surface V2O5 and Cr2O3 in a state of oxidation slightly higher than that in the absence of CO2. (C) 2003 Elsevier B.V. All rights reserved.