A 16-year-old boy was headbutting while he was waiting for a bus in Banbury town centre last Thursday.
At 5.30pm the victim was standing in a queue at the bus station in Bridge Street when he was approached from behind by a man he did not know.
The man then spoke to the victim before headbutting him, leaving the victim feeling dizzy. The victim attended the Horton General Hospital and has since been discharged.
The offender is white, aged approximately 19 to 20 years old, around 5ft 10ins, slim, with short hair. He was wearing sports clothing including grey tracksuit bottoms.
He was with another man who is white, approximately 5ft 10ins, slim, pale, had stubble and was approaching member s of the public while carrying a coin in his hand.
The offender was also with a woman who was aged approximately 19 to 20 years old, is pale with straight long hair and was wearing tight trousers. She was with a large black dog which appeared similar to a Staffordshire Bull Terrier.
Investigating officer PC Ruth Ivins, from Banbury police station, said: “I would like to speak to anyone who saw the incident as they may be able to help with police enquiries.
“If you have any information which could assist the investigation or recognise the description of the offender and those he was with please call us.”
If you have any information please contact PC Ivins via the 24-hour Thames Valley Police enquiry centre on 101. Alternatively call Crimestoppers anonymously on 0800 555 111.