Large-scale single crystalline vanadium oxide nanobelts were synthesized by hydrothermal treatment of NH4 VO3 in the presence of polymer PEG-4000 at 180 degrees C for 24h. Techniques of SEM, TEM, XRD, FT-IR, HRTEM, and SAED were used to characterize the morphology, composition and structure of the as-obtained nanobelts. The as-prepared vanadium oxide nanobelts are up to several hundreds micrometers in length, 100 nm-1 mu m in width, 20-30 nm in thickness, and grow along the [1 0 0] direction. PEG plays a critical role for the formation of the vanadium oxide nanobelts in the present synthetic system. A preliminary formation mechanism was proposed to account for the formation of the as-obtained nanobelts. (c) 2005 Published by Elsevier B.V.