Titanium monoxide (TiO), which is a versatile ceramic material with a low electrical resistivity and an extreme hardness, has received considerable attention for potential applications in decorative and protective coatings, and in microelectronic layered structures. In this study, a green and simple method to synthesize titanium monoxide (TiO) nanoparticles from commercial TiO micro sized powder through low-energy wet ball-milling is presented. The as-milled TiO powder shows good dispersibility in ethylene glycol, indicating a promising material for solution-based production. During annealing in a vacuum at 900 degrees C, the as-milled TiO powder transforms from monoclinic to cubic structure. The annealed TiO, in the form of a pellet, shows a very low electrical resistivity (2.1 m Omega cm). When dispersed in ethylene glycol, the annealed TiO powder almost preserves the optical property of the as-milled TiO by presenting a gradual increase in absorption from visible range to near-infrared region. Thus, low-energy wet ball-milling is an environmentally friendly and effective method to synthesize TiO nanopowder for a variety of purposes. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.