The influence of iron oxide, FeOx, on Pt for CO oxidation was investigated. A film of FeOx, nominally 0.8-nm thick, was added to a Pt/Al2O3 catalyst by Atomic Layer Deposition. The film was found to wet the Pt surface after oxidation at 773 K and 973 K, as shown by aberration-corrected, transmission electron microscopy. In-situ infrared spectra and CO chemisorption measurements showed that the addition of the FeOx greatly suppressed CO adsorption but enhanced CO oxidation rates due to FeOx-Pt interfaces. The FeOx layer also improved the stability of the catalyst by mitigating the sintering of Pt particles at 973 K.