In the last years, the combination of 2H solid-state NMR techniques with quantum-chemical calculations has evolved into a powerful spectroscopic tool for the characterization of the state of hydrogen on the surfaces of heterogeneous catalysts. In the present minireview, a brief summary of this development is given, in which investigations of the structure and dynamics of hydrogen in molecular complexes, clusters and nanoparticle systems are presented, aimed to understand the reaction mechanisms on the surface of hydrogenation catalysts. The surface state of deuterium/hydrogen is analyzed employing a combination of variable-temperature 2H static and magic-angle spinning (MAS) solid-state NMR techniques, in which the dominant quadrupolar interactions of deuterium give information on the binding situation and local symmetry of deuterium/hydrogen on molecular species. Using a correlation database from molecular complexes and clusters, the possibility to distinguish between terminal RuD, bridged Ru2D, three-fold Ru3D, and interstitial Ru6D is demonstrated. Combining these results with quantum-chemical density functional theory (DFT) calculations allows the interpretation of 2H solid-state data of complex “real world” nanostructures, which yielded new insights into reaction pathways at the molecular level.