The coating method and the characteristics of wire explosion spraying, as developed in our laboratory, are described. A study of the mechanism of adhesion between the coating and substrate in two metal systems, W-mild steel and W–Cu which differ in mutual solubility, is discussed. Metallographic observations using electron probe and soft x ray confirmed the presence of a solid solution boundary layer in the case of the mild steel substrate, with a critical shearing stress of adhesion measured by our method ranging from 20 to 26 kg/mm2, which is nearly equal to the shearing strength of the tungsten coating itself of 24 kg/mm2; fracture propagated within the coating itself. In the case of the copper substrate the critical shearing stress of adhesion was from 9 to 13 kg/mm2 which is much weaker than the shearing strength of copper, 28 kg/mm2; the fracture propagated along the boundary between the coating and substrate. Theoretical considerations attempt to explain the mechanisms of formation of the structures and the adhesion properties. It is concluded that the high adhesion strengths obtained by this method are attributable to the characteristics of the particles sprayed by wire explosion, i.e., the small size (average 5 μ), the high temperature (near the boiling point of materials), the high impinging velocity (500–600 m/sec), and furthermore, the uniformity of the size, velocity and temperature of the sprayed particles.