We present a series of experimental results indicating improved oxygen reduction characteristics on nanocrystalline yttria-stabilized zirconia (YSZ) surfaces. We compare (i) cathodic interface impedances on nanocrystalline and microcrystal line YSZ, (ii) oxygen exchange rate on and bulk diffusivity in nano- and single-crystal YSZ, and (iii) bulk and surface conductivities of nano-YSZ. The results collectively indicate that the oxygen reduction/exchange rate is faster on nanocrystalline YSZ than on micro- and single-crystal YSZ, which likely is related to fast oxygen or electronic transport on the surface. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3058597] All rights reserved.