Cubic Co3O4 nanocrystals (NCs) were synthesized by a one-pot hydrothermal reaction in the presence of the oxidant KClO3 and the capping reagent polyvinylpyrrolidone (PVP). The as-prepared Co3O4 NCs were uniformly cubic with sharp edges and good crystallinity and showed flat surfaces with (100) facets. The capped PVP could be removed without losing cubic shape by heating the NCs at 300 degrees C. (C) 2009 Elsevier B.V. All rights reserved.