Supported vanadium oxides are one of the most promising alternative catalysts for propane dehydrogenation (PDH) and massive efforts have been made to improve its catalytic performance. However, unlike Pt‐based catalysts, the nature of the active site and surface structure of supported vanadium catalysts under reductive reaction condition still remain elusive. We show that the surface structure and the important role of surface‐bound hydroxyls of VOx/Al2O3 catalysts under reaction conditions employing in situ DRIFTS experiments and DFT calculations.