The man, thought to be from Birmingham, collapsed at a Swansea nightclub during the event at the end of a party to raise funds for an art exhibition.
Police say there are no suspicious circumstances following the incident at the city's Monkey Cafe and Bar early on Friday.The coroner has been informed and the family have been told.
It is believed attempts were made by staff and customers at the nightclub to revive the man.
In a statement, club owners Amanda Davey and Paul Dyke said: "We are all devastated by this tragic accident.
"We are all in shock."It was a tragic accident and very sad and should serve as a cautionary tale."Our deepest sympathy goes out to his family."