Mo2C catalyzes propane dehydrogenation and hydrogenolysis at 823 K; carbon selectivity can be tuned to >95% propylene via dehydrogenation in absence of H-2, >95% CH4 via hydrogenolysis with H-2 co-feed, or >80% CO via reforming pathways with H-2 and CO2 co-feed. The changes in selectivity are mediated by an evolution in the coverage of oxidized (O*) and carbidic (*) surface sites which results in an evolution of O*-O*, O*-*, and *-* site pairs that catalyze propane dehydrogenation. The fraction of O* in relation to * was assessed from measured CO2/CO ratios because reverse water gas shift equilibrium exists under H-2/CO2 co-feed steady state reaction conditions. Kinetic models based on the two-site dehydrogenation mechanism could be used to quantitatively describe measured rates of propane dehydrogenation at steady state with or without H-2 and/or CO2 co-feed and the transient evolution in dehydrogenation rates upon removing H-2 or CO2 in the influent stream to note that O*-* site pairs exhibit the highest rate per gram. This model also provides a rationale for O* inhibition of H-activated hydrogenolysis pathways and for promotion of oxidative dehydrogenation rates with the introduction of hydrogen into CO2-propane influent streams. This study extends concepts developed for examining the catalytic effects of O* coverage on oxidative light alkane conversion from transition metal catalysts to also include carbidic formulations. (C) 2017 Elsevier Inc. All rights reserved.