Police and paramedics were called to Brighton seafront opposite The Old Ship Hotel in the early hours of Sunday morning (February 12) where a man had collapsed.
The man later died in hospital, and officers investigating the death are now appealing for witnesses.
Detective Inspector Jo Grantham said: “We have identified the man as a 39-year-old from Guildford who was visiting Brighton. We believe he left a nightclub in the Kings Road arches around 2.20am and last contact was made with him at around 3.30am.
“His death is being treated as unexplained at this time but not believed to be suspicious. However we are hoping to speak to anyone who might have seen him near The Old Ship Hotel or on the Upper Promenade on the southern side of the road between 2.15am and 7.10am on Sunday (February 12).
“He is a black man, around 6’ to 6’ 2” with a shaved head and trimmed beard, wearing grey jeans, beige boots, a mustard coloured shirt with a jacket worn over this.”
Anyone who saw anything which could help with the investigation is asked to contact police online quoting 0266 12/02/2017.