Niobium-incorporated Li3V2(PO4)(3) (LVP) with nominal formula Li3V2-xNbx(PO4)(3) cathode materials for lithium ion batteries are synthesized via two-step solid-state reaction. Significant improvement in capacity, rate capability and cyclability are achieved in the Nb-incorporated LVP/C composites compared with pristine LVP/C. The Nb-incorporated LVP/C composite with x 0.03 delivers an initial discharge capacity as high as 182 mAh g(-1) at 0.1 C and an excellent rate-capability with about 160 mAh g(-1) at 1 C and 125 mAh g(-1) at 5 C. Transmission electron microscopy and X-ray photoelectron spectroscopy clearly show the existence of beta-NbOPO4, demonstrating that Nb has not doped into the crystal lattice. Our experiments further indicate that the particle size is reduced and the electrical conductivity is enhanced for LVP with Nb-incorporation. The improvement in electrochemical performance can be contributed to the formation of beta-NbOPO4 and reduced particle size of LVP. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3598175] All rights reserved.