The present paper reports the production of nano-tungsten particles by the wire explosion process. The impact of ambient medium on the size of the particles produced is examined. The ambient gas with a high cooling rate is observed to result in smaller particles. Wide-angle X-ray diffraction (WAXD) studies were conducted to understand the chemical constituents and phases present in the produced powder. The composition of the material was studied through the energy dispersive analysis by X-rays (EDAX). The size of the particles was measured using a transmission electron microscope (TEM) and particle size distribution was determined by adopting a log-normal distribution. An attempt has been made to understand the temperature at which saturation ratio is maximum and when nucleation commences and leads to formation of nano-particles. © 2008 Elsevier B.V. All rights reserved.