Electrolysis is a method of producing fine and ultra-fine copper powders with high purity. In this paper the effects of current density (i), sulfuric acid concentration [H2SO4], copper (II) ion concentration [Cu2+] and chloride ion concentration [Cl-] on this process were studied. The considered parameters were varied as follows: current density, 025-0.35 A/cm(2); [H2SO4], 140-180 g/L; [Cu2+], 2-8 g/L; and [Cl-], 0-60 ppm. To optimize these parameters, nonregular fractional factorial design of experiments was used. Produced powders were characterized by X-ray diffraction (XRD), a scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and a Laser Particle Size Analyzer (LPSA). After surveying the results and analysis of variance, optimized parameters were determined and a mathematical model was presented. The optimum condition was: current density, 0.35 A/cm(2); [H2SO4], 140 g/L; [Cu2+], 2 g/L; and [Cl-] 0 ppm. The predicted particle size at the optimum condition was found to be 0.71 mu m which was very close to the experimental value of 0.68 mu m. (C) 2013 Elsevier B.V. All rights reserved.