Results of studying structure of the transition zone for a number of joints produced by explosive welding are presented. The joints of dissimilar metals (titanium-orthorhombic titanium aluminide, coppertantalum, and others) have been investigated. The welded pairs of metals differ from each other in mutual sol ubility; moreover, some pairs (copper-tantalum) virtually lack it. The interface was found to be uneven; it contains inhomogeneities, irrespective of whether it is flat or wavy. It is shown that the formation of interfacial protrusions determines the adhesion of materials. A granulating fragmentation has been found near the pro trusions. The role of various processes in explosive welding has been discussed. The formation of protrusions does not depend on whether the metals of a pair have mutual solubility or not. However, this factor affects the structure of zones of local melting. The metals that have mutual solubility form true solutions; in the absence of solubility, these zones represent colloidal solutions. It is shown that sometimes the local melting zones do not present a real danger for the strength of the joint. A hypothesis is proposed that the formation of a wavy surface is possible through the self organization of the previously formed protrusions.