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Composite, Solid-Oxide-Fuel-Cell (SOFC) electrodes of La0.8Sr0.2FeO3 (LSF) and yttria-stabilized zirconia (YSZ) were prepared by infiltration methods and then modified by Atomic Layer Deposition (ALD) of ZrO2, La2O3, Fe2O3, or La2O3-Fe2O3 codeposited films of different thicknesses to determine the effect of surface composition on cathode performance. Film growth rates for ALD performed using vacuum procedures at 573 K for Fe2O3 and 523 K for ZrO2 and La2O3 were determined to be 0.024 nm ZrO2/cycle, 0.019 nm La2O3/cycle, and 0.018 nm Fe2O3/cycle. For ZrO2 and Fe2O3, impedance spectra on symmetric cells at 873 K indicated that polarization resistances increased with coverage in a manner suggesting simple blocking of O2 adsorption sites. With La2O3, the polarization resistance decreased with small numbers of ALD cycles before again increasing at higher coverages. When La2O3 and Fe2O3 were co-deposited, the polarization resistances remained low at high film coverages, implying that O2 adsorption sites were formed on the co-deposited films. The implications of these results for future SOFC electrode development are discussed. © The Author(s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0181709jes] All rights reserved.