A 48-year-old man has died in hospital after a one-punch attack in South Brisbane on Saturday morning.

Timothy Lang died from his injuries in the Princess Alexandra Hospital on Monday afternoon and detectives were still searching for his attacker.

Police released vision of a man who might be able to help with the investigation. He was described as about 170cm with short dark hair, wearing black shorts with a red shirt tucked into them and white running shoes.

The incident happened about 10.15am on Saturday when a man was walking along Melbourne Street became involved in an argument with another man who was jogging in the opposite direction.