Weakly agglomerated nanocrystalline (ZrO2)(0.92)(Sc2O3)(0.08) (8ScSZ) powders (6.7 nm in size) in fluorite cubic structure were synthesized by a two-step hydrothermal process in the presence of urea: a stock solution containing metal nitrates and urea was heated at 80 degreesC for 24 h and then at 180 degreesC for 48 h. Dense 8ScSZ ceramic samples with grain sizes ranging from 60 nm to 6 mum were fabricated by isostatically pressing the as-prepared powders followed by sintering at 1000-1400degreesC. The bulk conductivities of the samples were considerably higher than those reported in the literatures especially at low temperature range. A significant enhancement of the specific grain boundary conductivity was also found when the grain size was reduced to the nanometer regime. (C) 2003 Elsevier B.V. All rights reserved.