Copper nanoparticles are prepared in aqueous solution by reducing copper ions with hydrazine hydrate in the presence of cetyl trimethylammonium bromide (CTAB) and polyvinylpyrrolydone (PVP) as stabilizers. With only CTAB was used as stabilizer, copper nanoparticles are aggregated and partially oxidized to Cu(2)O. When both PVP and CTAB were used, dispersed copper nanoparticles with 56 nm diameter were obtained. Copper nanoparticles are simply mixed with poly (3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) in aqueous solution to form conducting composite. The effect of copper weight percent and surfactants on the conductivity and stability of the composite has been investigated. (C) 2011 Elsevier Inc. All rights reserved.