The robbery happened around 6:00 a.m. on Thursday, May 2nd.
Investigators say the victim had just gotten off the Route 60 bus at Front Street and Allegheny Avenue and was being followed by the suspect.
The victim used his phone to call police and the suspect, hearing his conversation, approached him and struck him in the face with the gun.
The suspect then fled north on Hope Street toward Westmoreland Street.
According to police, the man is known to frequent the Route 60 bus stop.
The suspect is described as a black male, 40 to 50 years of age, 5'10" tall, weighing 175 pounds with a medium build and a scruffy beard. He was wearing a dark-colored Yankees baseball cap, dark jacket and blue jeans.
Anyone with information is asked to contact Philadelphia Police at 215-686-TIPS (8477), text a tip to PPD TIP (774847) or through PhillyPolice.com.