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DFT calculations coupled with IR spectroscopy measurements precisely identify location of active isolated Ru+2 cations on ceria. Upon NO adsorption, NO donates an electron to a Ce4+ center, thus NO+ ligand and a Ce3+ center are formed, while the formal charge of the Ru remains +2. FTIR measurements reveal the formation of remarkably stable Ru(II)(NO) complexes as well as spill-over of NO to CeO2 surface via the Ru-O-Ce shuttle, explaining high NO storage. Notably, Ru/ceria survives hydrothermal aging in air/water vapor at 750 â°C without evaporation of atomically dispersed ruthenium, and as a consequence shows no loss of PNA capacity. NOx related applications of this new material are not constrained by it being a stable NOx storage materials: Ru/ceria is also a robust NO oxidation catalyst, considerably more active than Pt or Pd/CeO2 and comparable to the best industrial catalysts based on more expensive Pd and Pt. Expanding the repertoire of Ru/CeO2 catalytic applications, we further find 0.1 and 0.5 wt% Ru/CeO2 to be excellent TWC catalysts, rivaling best single-atom Rh-containing uber-expensive supported materials. Our study pushes the frontier of precious metal atom economy for environmental catalysis from ultra-expensive Rh/Pd/Pt to more sustainable cheaper Ru and highlights the utility of single-atom catalysts for identifying previously unknown materials for industrially relevant applications.