In this paper, a simple, safe and cost-saving precipitation-peptization method was proposed to prepare VO2 sol by using inorganic VOSO4-NH3 center dot H2O-H2O2 reactants system in air under room temperature. In this process, VOSO4 was firstly precipitated to form VO(OH)(2), then monometallic species of VO(O-2) (OH)(-) were formed through the coordination between VO(OH)(2) and H2O2. The rearrangement of VU (O-2)(OH)(-) in a nonplanar pattern and intermolecular condensation reactions result in multinuclear species. Finally, VO2 sol is prepared through the condensation reactions between the multinuclear species. After drying the obtained sol at 40 degrees C, VO2 xerogel exhibiting monoclinic crystal structure with the space group of C2/m was prepared. The crystal structure of VO2 nanoparticles was transferred to monoclinic crystal structure with the space group of P2(1/c) (VO2(M)) by annealing the xerogel at 550 degrees C. Both XRD and TEM analysis indicated that the nanoparticles possess good crystallinity with crystallite size of 34.5 nm as estimated by Scherrer's method. These results suggest that the VO2 sol has been prepared successfully through the proposed simple method. (C) 2015 Elsevier Inc. All rights reserved.