Densely distributed copper nanoparticles have been deposited on the surface of carbon nanotubes with a size of similar to10 nm by the electroless plating method. It has been found that the pretreatment of the carbon nanotubes is very important to obtain the copper nanoparticles on the carbon nanotubes; in our experiments, one-step pretreatment of mixed HNO3 and H2SO4 was found effective. In order to attain nanosized copper particles, the electroless plating parameters should be closely controlled; e.g., the pH value of the plating solution, the temperature, and the concentration and titrating speed of HCOH were critical. (C) 2004 Elsevier Ltd. All rights reserved.