Highly stable dispersions of copper nanoparticles with an average particle size of about 2 nm were synthesized via a simple and cost-effective one-pot method with CS2 as a reactant and a solvent as well for synthesizing surface-capping agent and Cu nanoparticles. As-prepared copper nanoparticles were characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and Fourier transform infrared spectrometry. It has been found that surface-capped copper nanoparticles with a narrow size distribution can be readily fabricated with the established method. As-obtained spherical surface-capped Cu nanoparticles can form stable dispersions which do not show any sign of sediment even after storage at ambient conditions for 6 months, showing promising potential as novel lubricant additive. (C) 2013 Elsevier Ltd. All rights reserved.