Although demonstrations of significant improvement in the photocatalytic activity of TiO2-RGO composites are numerous, 6,7,19,20,61−63 a closer examination of the specific interactions between TiO2 and RGO in aqueous suspension are needed to better understand its limitations in practical applications. Of specific importance is the direct reaction between OH• and RGO because of the prevalence of these radicals when irradiating TiO2 in aqueous media. In ourprevious work, we have shown the susceptibility of the C=C bonds in RGO to OH• radical attack, which were assisted by gold nanoparticles to formulate holey-graphene suspensions.60 The potential for oxidative fragmentation of the RGO sheets into smaller PAH domains via OH• attack may render the environmental benefits of using TiO2-RGO composites in photocatalytic pollutant degradation moot because new environmental concerns would be generated in the process. In this study, we focus specifically on the susceptibility of RGO toward OH• attack promoted by UV-irradiated TiO2 suspensions and elucidate the role of OH• radicals in inducing the oxidation. The study provides new insight into the fate of RGO in an oxidative photocatalytic environment and raises concerns about its long-term stability