An account of some of the principal lines of research and development pursued, during the late war, to solve the complex and changing problems presented by the designers of enemy bombs, which resulted in the devising of methods, apparatus, and equipment for use by the Unexploded Bomb Disposal Sections of the three Services. The three primary problems of bomb disposal are described: the location of the bomb; the rendering safe of fuzes, and anti-handling and booby-trap devices; and opening and emptying the bomb of its high-explosive filling. The considerable variety of fuzes—and their associated devices—fall into certain groups, and the technically important types of those encountered are described. As the result of intensive investigations, a large proportion of which could only be carried out on live bombs, satisfactory disposal techniques were developed, and suitable field equipment was designed and produced for use in this country and overseas theatres of war. The lecture deals primarily with German high-explosive general-bombardment bombs, but some mention is made of Italian and Japanese bombs, as well as the German flying-bomb and long-range rocket.