We synthesized monodispersed copper sulfide (CuxS) NCs at nearly ambient temperature. Alkan thiol and amphiphilic amine mixture (ligand mixture) enable us to use relatively low toxic, stable and low cost materials as metal and sulfur source. Furthermore, oleylamine (OA) and dodecanethiol (DT) play important roles to control Cu/S composition on NCs. This compositional change of Cu,S NCs was attributed to the introducing of S-S bonding (S-n(2-)) into NCs. (C) 2007 Elsevier Ltd. All rights reserved.