British chemist Martin Fleischmann, who stunned the world by announcing that he had achieved nuclear fusion in a glass bottle, has died after a long illness.

His son Nicholas said he died Friday at his home in England.

Fleischmann was one of the world's leading electrochemists when he and partner Stanley Pons proclaimed in 1989 that they had sparked fusion, the nuclear process that heats the sun, in an experiment at the University of Utah.

The reaction they reported occurred at room temperature and appeared to give off little radiation, an enormous contrast to the still-ongoing quest to harness fusion by conventional means, in billion-dollar reactors at temperatures of millions of degrees.

The announcement raised the hope of a shortcut to fusion as a clean, renewable and cheap energy source. But when other scientists rushed to replicate the achievement, most failed, and "cold fusion" was quickly labeled junk science. Physicists accused Fleischmann of incompetence and fraud.

He and Pons continued to work on — and defend — their findings, but they were disheartened by the way their work was ignored by scientists after the debacle of 1989.

"This has been a terrible experience," Fleischmann told German news site Telepolis in 2005.

Research on "cold fusion" persists on the fringes of the scientific world.

Fleischmann was born in Czechoslovakia. When the Nazis occupied the country in 1938, the family fled to England. To gain legal status for the move, Fleischmann was adopted by a British bachelor.

He studied chemistry at the Imperial College in London and became known for a strong grasp of mathematics and an imagination unusual for a chemist. He took over the chemistry department of the University of Southampton in 1967 and gave it an international reputation. He was a fellow of the Royal Society, Britain's Academy of Sciences.

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After retiring from the university, he spent a lot of time collaborating on experiments with his friend Pons, an American.

Fleischmann was an "exploratory genius," said Michael Melich, a friend of Fleischmann and a research professor of physics at the Naval Postgraduate School in California.