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The reaction mechanism of the reverse water–gas shift reaction (rWGSR) over Au/ceria catalysts was investigated by monitoring the catalyst dynamics and reaction intermediates using operando and transient spectroscopies, as well as by DFT calculations. Combined operando Raman and UV-Vis spectroscopic analysis allows establishing a correlation between subsurface oxygen vacancies and catalytic activity. Comparison of different ceria support materials, i.e., polyhedra and polycrystalline sheets, reveals that the defect concentration is not rate-determinant. Using transient DRIFTS, we are able to identify individual steps of hydrogen dissociation on supported gold and to gain detailed insight into the reduction of CO₂ via formate and carbonate formation. It is demonstrated that CO₂ reduction is influenced by the surface pretreatment. Considering all spectroscopic findings, we propose an associative mechanism via carbonate and formate intermediates as the main route for the rWGSR over Au/ceria(111) catalysts, while a redox mechanism plays only a minor role.