Different morphological MoO2 nano-sized particles were synthesized by a low temperature hydrothermal reaction as a novel method. The physical characterizations were carried out by IR, TG/DTA, XRD, XPS, SEM, TEM and SAED. XRD and XPS data indicate the as-prepared samples present at pure phase MoO2 with monocline symmetry. Spherical, sheet-like and bar-shaped nano-particles are observed by SEM, respectively. The lithium-intercalation properties of spherical MoO2 powders were investigated by XRD, TEM and SAED in the light of bulk MoO2. The results showed an irreversible phase transition after the initial discharge process, which is obviously different from the bulk sample. (c) 2005 Elsevier B.V. All rights reserved.