A 15-year-old boy was punched in the face in an arcade in Chapel St Leonards.
The alleged assault occurred in an arcade on Trunch Lane, at around 8.30pm on Thursday, August 25.
Investigating officers have said that the suspect is a black man, of large build, who was in the company of two other black men and a white man.
All are believed to be aged between 17 and 20.
PC Dan Healey of Lincolnshire Police is keen to trace the man captured on CCTV who may be able to help the force with the investigation.
Anyone who knows the man, or has information about incident, should contact PC Healey on 101, quoting incident number 524 of August 25.