Sinter-resistant catalyst systems include a catalytic substrate comprising a plurality of metal catalytic nanoparticles bound to a metal oxide catalyst support, and a coating of oxide nanoparticles disposed on the metal catalytic nanoparticles and optionally on the metal oxide support. The oxide nanoparticles comprise one or more lanthanum oxides and optionally one or more barium oxides, and additionally one or more oxides of aluminum, cerium, zirconium, titanium, silicon, magnesium, zinc, iron, strontium, and calcium. The metal catalytic nanoparticles can include ruthenium, rhodium, palladium, osmium, iridium, and platinum, rhenium, copper, silver, and/or gold. The metal oxide catalyst support can include one or more metal oxides selected from the group consisting of Al2O3, CeO2, ZrO2, TiO2, SiO2, La2O3, MgO, and ZnO. The coating of oxide nanoparticles is about 0.1% to about 50% lanthanum and barium oxides. The oxide nanoparticles can further include one or more oxides of magnesium and/or cobalt.