Hofmann died on Tuesday of a heart attack at his home in Basel, Switzerland, said Rick Doblin, president of the Multidisciplinary Association for Psychedelic Studies, in a statement posted on the association's website.

Hofmann's hallucinogen inspired - and arguably corrupted - millions in the 1960s hippy generation. For decades after LSD was banned in the late 1960s, Hofmann defended his invention.

"I produced the substance as a medicine ... It's not my fault if people abused it," he once said.

The Swiss chemist discovered lysergic acid diethylamide-25 in 1938 while studying the medicinal uses of a fungus found on wheat and other grains at the Sandoz pharmaceuticals firm in Basel.

He became the first human guinea pig of the drug when a tiny amount of the substance seeped on to his finger during a repeat of the laboratory experiment on April 16 1943.

"I had to leave work for home because I was suddenly hit by a sudden feeling of unease and mild dizziness," he subsequently wrote in a memo to company bosses.

"Everything I saw was distorted as in a warped mirror," he said, describing his bicycle ride home. "I had the impression I was rooted to the spot. But my assistant told me we were actually going very fast."

Three days later, Hofmann experimented with a larger dose. The result was a horror trip.

"The substance which I wanted to experiment with took over me. I was filled with an overwhelming fear that I would go crazy. I was transported to a different world, a different time," Hofmann wrote.