Moving beyond identification of sites purely on the basis of chemical shift, Ga NMR has been successfully used to probe the nature of sites in minerals and molecules, where NMR, often in combination with density functional theory (DFT) methods, is used for direct structural characterization of Ga sites. However, the application of 69/71 Ga NMR for direct structural characterization of catalytically-relevant surface sites is hampered by poor sensitivity, due to low Ga weight-loadings as well as the distorted nature of surface sites, resulting in signal broadening associated with a distribution of quadrupolar couplings. Nevertheless, 69/71 Ga NMR would be a valuable tool for obtaining structural insights into surface Ga-sites in heterogeneous catalysts. For this purpose, the favourable Larmor frequency and lower electric quadrupole moment mean that Ga is the nucleus of choice for such studies, in spite of the lower isotopic abundance of Ga with respect to Ga. Here, using Ga ss-NMR in combination with probe molecule studies, complemented by synthesis of molecular analogs and DFT calculations, the structure of Brønsted acidic and Lewis acid surface sites in a Ga-based alkane dehydrogenation catalyst are elucidated (Figure ). Concurrently, the influence of probe molecules on the 71 Ga NMR spectroscopic signature is investigated, and interactions with specific probe molecules are rationalized.