In this work, the transport properties of fine-grained scandia-stabilized zirconia ceramics with low Si content have been investigated. These materials were prepared from ZrO2-6 mol% Sc2O3 nanopowders synthesized by a nitrate-lysine gel-combustion route. High relative densities and excellent electrical properties were obtained, even for sintering temperatures as low as 1350 degrees C. Our electrochemical impedance spectroscopy study showed that both the volume fraction of grain boundaries and the specific grain-boundary conductivity are significantly enhanced with decreasing grain size, resulting in a higher total ionic conductivity. (C) 2009 Elsevier B.V. All rights reserved.