Nanocrystalline powders synthesized by mechanochemical activation were successfully used to process high-density submicron- and nanostructured 0.8Pb(Mg1/3Nb2/3)O-3-0.2PbTiO(3) perovskite phase ceramics by hot pressing, with average grain size ranging from 0.36 mu m down to 88 nm. These materials are very suitable for studying the size dependence of the properties across the submicron range approaching the nanoscale. This is the first report of such a series of ceramic materials of a relaxor-based morphotropic phase boundary composition, and of its properties as a function of the grain size. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.