Saleh Mordi was reported missing on October 12 after he failed to return to his home address in Leeds, police said.
Officers believe he could have travelled to the Sheffield area.
A West Yorkshire Police spokesperson said: "He’s described as a black male, six foot tall, of medium build and brown eyes.
"He was last seen wearing a camouflage jacket, black trousers and grey trainers.
"There haven’t been any sightings of Salah since October 13 and police and his family are concerned with his welfare."
Anyone with information about his whereabouts should call police on 101.