The hydrogen bomb was a 20th century weapon. It was capable of great destruction. Protesters from the Campaign for Nuclear Disarmament annually marched in protest of the weapon. (PROSE: Come Friendly Bombs...)
When Caven attempted to create a blast "the equivalent of about eighty old-fashioned hydrogen bombs" by hooking up twenty demolition charges to the atomic fuel store, the Second Doctor dismantled the detonator and avoided the explosion. (TV: The Space Pirates)
An H-bomb lost off the coast of Spain affected the sea creatures living there, slowly mutating them to giant size. Two thousand years later, in the 40th century (a time in which the H-bomb was considered obsolete), the creatures were discovered by Pete Nesbit of the Marine Rescue Brigade, who destroyed them by detonating the bomb. (COMIC: The Sea Monsters)