Contemporary art collectors opened their wallets and shelled out $US42.6 million ($A47.29 million) at a Valentine's Day charity auction spearheaded by rocker Bono and British artist Damien Hirst to benefit the fight against AIDS in Africa.

Spirited bidding and prices far in excess of pre-sale estimates marked "The (Red) Auction" at Sotheby's, where all but one of the 83 contemporary works, each donated by the artists or their estates, found buyers.

The $US42,584,300 ($A47.27 million) total easily eclipsed even the highest expectations of about $US29 million ($A32.19 million) for the sale, which Sotheby's said was among the biggest single charity events in history.

Proceeds from the sale were earmarked for the United Nations' Global Fund's fight against AIDS in Africa in conjunction with Bono's "Red" brand, wherein products from major corporations including Apple, the Gap, Microsoft and Hallmark have generated $58 million for AIDS.

"This was a really historic night," said Bono, sporting his trademark sunglasses.

"I'm really very, very moved," he said, having "seen people dying for lack of the two pills a day" it takes to treat AIDS.

While contemporary artists have been among the chief beneficiaries of the art market boom of the past decade, Bono said, "They're the heroes tonight."

"I can't get over the selfless acts of the artists," he said before leading the packed salesroom into joining his a Capella rendition of All You Need Is Love, a somewhat surreal and in all likelihood unprecedented, scene in the rarefied auction world.

Among those gathered for the bidding were rap impresario Russell Simmons, TV host and publishing mogul Martha Stewart, Jordan's Queen Noor, rocker Michael Stipe and former tennis star John McEnroe. Bidding - some of it by telephone - was aggressive at all levels with works soaring to two, three and even 10 times their estimates.

Hirst contributed seven works, including Where there's a will there's a way, a monumental medicine chest sculpture containing hundreds of metal HIV pills that fetched $US7.15 million ($A7.94 million). It had been the sale's top-priced lot, estimated to bring $US5 million ($A5.55 million) to $US7 million ($A7.77 million).

Five Hirsts were among the top 10 lots in the sale, which also set 17 artist's records. Sotheby's lowered its commission for the auction and made no profit, using the 10 per cent fee to fund the event's costs and donating any remainder to the UN fund.

Many but not all of the 83 works on offer were specially created for the Valentine's Day auction and were rendered in vibrant shades of red, or used the colour as a thematic element.