Nano tungsten oxide particles are produced by wire explosion process. It is realized that by exploding tungsten conductor in lower pressure of oxygen, unreacted phase of tungsten was present and it could be reduced by increasing the operating pressure and increasing the amount of energy deposited to the exploding conductor. It is realized that the nucleation rate of the particle could be high only at the point of maximum saturation ratio, irrespective of the pressure of the oxygen. The size of the critical nucleus formed is low when the saturation ratio and the nucleation rate are at maximum. The nano metal oxide particle formation by wire explosion process allows one to conclude that the second stage annealing process has a major impact on the final grain size formed. The high speed camera photographs of wire explosion process were used to understand the dynamics of particle formation by wire explosion process. The Transmission Electron Microscopy (TEM) analysis indicates that the nano tungsten oxide (WO3) particles are of spherical shape and the analysis of particle size indicates that it follows log normal distribution. © 2010 Elsevier Inc. All rights reserved.