Hayes was found by family members, who discovered him lying next to a treadmill in a basement room at his home. Sheriff's deputies performed CPR until paramedics arrived. He was taken to hospital but was pronounced dead an hour later.

Hayes, a distinctive and flamboyant figure among the black rhythm and blues stars of the early 1970s, found fame later in his career as the voice of Chef, the laid-back womaniser on the cartoon series South Park. But it was his hit song for the soundtrack of the blaxploitation movie Shaft that made and cemented his reputation. H e gave a memorable performance of it at the Oscar ceremony in 1972, scooping the Academy Award for best original song. The song and the film soundtrack also won him two Grammy awards.

Hayes also pursued an acting career, with cameos in several movies including Escape from New York, Robin Hood: Men in Tights and the blaxploitation spoof I'm Gonna Git You Sucka.

In the 1990s Hayes reached a new generation as Chef. Two years ago, however, he left the show after an episode that he felt made fun of the Scientology movement, of which he was a member.

A businessman who owned two restaurants and wrote a best-selling cook book, Hayes was married four times and had 12 children.