Redox stability of cubic nanostructured zirconia ceramics, free of any secondary phases, has been investigated experimentally as a function of grain size. Pure 8 mol% Y2O3-doped ZrO2 powders were synthesized by a spray pyrolysis process and then compacted by uniaxial pressing, followed by cold isostatic pressing. Using appropriate thermal treatments, average grain sizes ranging from 25 to 242 nm and relative densities from 71% up to 98% were obtained. An electrochemical characterization was performed with comparison on ceramics of 3.2 and 7.6 mu m and 98% of theoretical density starting from commercial YSZ powder. (C) 2009 Elsevier B.V. All rights reserved.