The adsorption of CO2on polycrystalline molybdenum is blocked even by the partial (aproximately two‐thirds) presence of the strongly bound β2oxygen. Pre‐adsorption of CO2at room temperature does not impede subsequent oxidation. The CO2adsorption kinetics at room temperature can be explained by a two‐site adsorption model with rapid dissociative chemisorption and carbon and oxygen in equivalent sites. On heating the CO2‐saturated surface above 900 K, CO is lost from the surface. Interaction of CO2at 1200 K gives a small buildup of carbon until the surface oxygen concentration increases sufficiently that the loss rate exceeds the deposition rate.