Cobalt-manganese ferrites were synthesized by the mechanochemical synthesis using metal salts as a precursor and sodium chloride as a growth agent. The dependence of the size and the magnetic properties of the prepared nanoparticles on the high-energy ball milling conditions were investigated. Cobalt manganese ferrite nanoparticles were characterized using the Mossbauer spectroscopy, atomic force microscopy (AFM) and X-ray diffraction. Measurements showed that the particle size of the cobalt ferrite nanoparticles varied from 4 nm up to similar to 10 nm without and with the addition of sodium chloride respectively whereas no such effect of the sodium chloride on manganese nanoparticles was observed. (C) 2015 Elsevier B.V. All rights reserved.