The photochemical properties of the Cr-terminated α-Cr 2 O 3 (0001) surface were explored using methyl bromide (CH 3 Br) as a probe molecule. CH 3 Br adsorbed and desorbed molecularly from the Cr-terminated α-Cr 2 O 3 (0001) surface without detectable thermal decomposition. Temperature programmed desorption (TPD) revealed a CH 3 Br desorption state at 240K for coverages up to 0.5ML, followed by more weakly bound molecules desorbing at 175K for coverages up to 1ML. Multilayer exposures led to desorption at ~130K. The CH 3 Br sticking coefficient was unity at 105K for coverages up to monolayer saturation, but decreased as the multilayer formed. In contrast, pre-oxidation of the surface (using an oxygen plasma source) led to capping of surface Cr 3+ sites and near complete removal of CH 3 Br TPD states above 150K. The photochemistry of chemisorbed CH 3 Br was explored on the Cr-terminated surface using post-irradiation TPD and photon stimulated desorption (PSD). Irradiation of adsorbed CH 3 Br with broad band light from a Hg arc lamp resulted in both photodesorption and photodecomposition of the parent molecule at a combined cross section of ~10 −22 cm 2 . Photodissociation of the CH 3 –Br bond was evidenced by both CH 3 detected in PSD and Br atoms left on the surface. Use of a 385nm cut-off filter effectively shut down the photodissociation pathway but not the parent molecule photodesorption process. From these observations it is inferred that d-to-d transitions in α-Cr 2 O 3 , occurring at photon energies <3eV, do not significantly promote photodecomposition of adsorbed CH 3 Br. It is unclear to what extent band-to-band versus direct CH 3 Br photolysis play in CH 3 –Br bond dissociation initiated by more energetic photons.