Metal oxide nanoparticles have been raising increasing interest. In this work, spinel cobalt oxide (Co3O4) nanoparticles of around 29 nm were synthesized using a modified polymeric precursor method. This method is based on the complexation of polyacrylate and cobalt ions in aqueous media by a chelation reaction, resulting in the synthesis of crystalline nanoparticles, confirmed by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). Some advantages of this technique are the fast, simple and efficient synthesis of nanoparticles after only 2 h of thermal decomposition at 480 degrees C and elimination of the aging step, which is an essential step in polymeric precursor-based methods such as sol-gel. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.