The growth of tungsten oxide nanowires on silicon substrates without using any catalyst is demonstrated by means of close-spaced vapor transport (CSVT) technique at atmospheric pressure. The source was formerly prepared from a tungsten foil to produce a tungsten oxide film. CSVT array is completed with silicon substrates located at a distance of ~350 m over the tungsten oxide source at moderate temperatures (~750°C). Two distinct kinds of nanostructures were produced; a uniform distribution of free standing tungsten oxide wires of several micrometers in length with diameters less than 150 nm; and wires assembled to form nanowire bundle. The X-ray diffraction characterizations show that the phases of WO2.7 and WO2.9 are present.