A highly efficient method, using ultrafine aluminum powder as heterogeneous reducing media as well as sacrificial template. has been developed to prepare various metallic or oxide nanoparticles including Au, Ag, Pt, RuO2 and Cu2O with good monodispersity. With the aid of ultrasonication-incluced physical effects such as acoustic cavitation and microstreaming, zerovalent metallic atoms or clusters, when generated, are immediately dislodged from the surface of aluminum powder and are driven into bulk solution phase, avoiding the surface deposition and reaction termination. Ultrasonication also plays a critical role in promoting the mass transport through the channels in the amorphous and porous Al2O3 passivation layer around aluminum particles. The method opens a general and potent avenue for preparation of high-quality nanoparticles in large quantity and in a way that is environmentally friendly. (C) 2008 Elsevier B.V. All rights reserved.