We report a seedless synthetic method of gold octahedral nanoparticles in an aqueous phase. Eight facets with {1 1 1} crystalline structures of octahedral nanoparticles could be formed in an aqueous medium when the gold salt was reduced by ascorbic acid at room temperature in the presence of cetyltrimethylammonium bromide as a shape-inducing agent, and hydrogen peroxide as a reaction promoter. The growth kinetics and surface crystalline structures were characterized by UV-vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy. (C) 2008 Elsevier Inc. All rights reserved.