A detonating device for explosive grenades whose firing bolt is fastened by means of a solder joint to a casing which is firmly connected to a retaining body and contains a heating charge, characterised in that a firing bolt 1 is displaced, once the solder joint F has softened, under the influence of a spring 7 (against the direction of flight of the grenade) until it stops against a recess 8 in the retaining body 9. <IMAGE>
