The only man ever to win two unshared Nobel prizes in different fields, Pauling was once ranked by the New Scientist alongside Isaac Newton, Marie Curie and Albert Einstein as one of the 20 most important scientists of all time.
''I think a person of Dr Pauling's stature only comes around once or twice a century,' said Steve Lawson of the Pauling Insitute, who announced the death. 'His colleagues here . . . share my sense of loss at his passing.'
His pioneering work in chemistry in the 1920s and 1930s on the structure of molecules established him as a giant of contemporary science.
In the 1950s and 1960s, he was at the forefront of a campaign against nuclear tests and was given some of the credit for the ban on detonating nuclear devices in the atmosphere.
He liked to recall that in 1962 he picketed the White House in an anti-nuclear demonstration and a few hours later was received there as a guest of President Kennedy.
But he was also the target of derision from his scientific colleagues for his tireless promotion of the health benefits of vitamin C.
Pauling's 1970 book, Vitamin C and the Common Cold, set out his theory that large doses of the vitamin can help to prevent or treat illness. He later suggested that it was beneficial for almost any ailment, including cancer and Aids. But most independent tests failed to support his claims.
Pauling's crusade hurt his credibility and his critics even accused him of sloppy research. Undaunted, he continued his work at the Linus Pauling Institute of Science and Medicine in Palo Alto, south of San Francisco.
Gaunt and white-haired, but with sparkling blue eyes and still vigorous in his nineties, Pauling practised what he preached by swallowing huge quantities of vitamin C as part of his daily routine - plus a little extra if he felt ill.
Pauling was born in Portland, Oregon, on 28 February, 1901, and was educated in Oregon and California.
In 1922 he began a 41-year association with the California Institute of Technology, where he carried out his seminal work on the chemical bond, or how molecules are held together.
In a 1981 interview, Pauling said he was most proud of his work between 1928 and 1935 because 'it changed the whole field of chemistry'.
As he celebrated his 90th birthday in 1991, Pauling was still probing the mysteries of the natural world and protesting at the follies of governments. A man with a remarkable memory, he continued to work nearly every day.
He still travelled to scientific meetings around the world, and when President Bush launched a war in 1991 to force Iraqi forces out of Kuwait, Pauling fired off a letter of protest to the White House.
Although he won a presidential medal for work on explosives during the Second World War, the dropping of the atomic bomb on Hiroshima in 1945 converted him and his wife, Ava, whom he married in 1923, into anti-war political activists. She died in 1981.
Pauling's peace work during the anti-Communist witch hunts after the war made him unpopular with the academic and political establishments, and he was refused a passport for two years.
It was returned to him when he won his first Nobel prize, for chemistry, in 1954 and needed to go abroad to accept it.
In 1962, his anti-war work brought him the Nobel Peace Prize, and he also become the first non-Soviet citizen to win Moscow's two top awards, the Lenin Peace Prize and the Lomonosov Medal.
He also campaigned against smoking and, despite having three sons and a daughter, for a limit of two children per couple.
Controversy cropped up in 1978 when Arthur Robinson, co-founder of the Pauling Institute, was fired.
Dr Robinson alleged that he was victimised because his studies failed to support Pauling's theories on vitamin C, and in 1983 the institute paid dollars 575,000 (now pounds 370,000) in settlement.
Pauling shrugged off this setback and continued his research, financed by thousands of small-scale donors.
'I enjoy looking for something that doesn't fit in with my picture of the world,' Pauling said in a 1990 interview. He added that he did not consider himself cleverer than other scientists, just more persistent in trying to understand the world.
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