The catalytic dehydrogenation of ethane is a potential alternative for the production of ethylene if significant improvements can be made in selectivity compared to the homogeneous free radical chain reaction mechanism inherent with steam cracking. Chromia-based catalysts have found use in the catalytic dehydrogenation of butanes, and have been examined as candidates for ethane dehydrogenation. While C-H bond activation has been established as the rate limiting step, little is known about what controls selectivity over chromia catalysts. The reactivity of different alkyl species (ethyl, ethylidene, ethylidyne) has been examined over single-crystal Cr₂O₃ with thermal desorption. The observed chemistry will be described in relation to known selectivity issues over supported chromia catalysts.