Fleischmann and Pons’s experiment is legendary: by dropping their cathode into water and running current through the system, the pair theorized that hydrogen atoms released by the water would then be absorbed by the palladium cathode. They further predicted that the loose hydrogen atoms would fuse with those in the palladium, releasing energy. They famously reported results that showed their jar water heating up far beyond what would be expected from the electrical input or from a chemical reaction, and thus they concluded that it must have been the result of nuclear activity. That assertion blew up in the media, with every major outlet reporting on it at the time. Unfortunately for the two, their results could never be replicated by outside sources.
An New York Times obituary explains the backlash thus: "One of the first hints that the news was too good to be true, skeptics said, was that both scientists were alive. Had there been as significant a nuclear reaction as they claimed, critics argued, they would have been killed by the radiation. Scientists around the world then tried, without success, to replicate the experiment. Panels for the American Physical Society and the federal Energy Department soon discredited their findings.""