MoO3 nanofibers have been synthesized by hydrothermal reaction from acidified ammonium heptamolybdate tetrahydrate precursor. Characterization included X-ray diffraction (XRD), scanning electron microscopy (SEM), SQUID magnetometry and Raman scattering (RS) spectroscopy. Structural analysis shows that MoO3 nanofibers 50-80 nm in diameter and a several micrometers in length are grown in the orthorhombic system (Pbnm S.G.). The composition MoO2.9975 was determined by Rietveld refinement and magnetic susceptibility measurements. The electrochemical performance of Li//MoO3 cells with nanofibers deliver a better discharge capacity after 40 cycles than MoO3 bulk. Raman spectroscopy studies revealed the structural modulation upon Li intercalation in MoO3 nanofibers. The possible mechanism of intercalation is discussed. (C) 2012 Elsevier B.V. All rights reserved.