Police were called to two men fighting in High Street in Cowley around 12.30pm yesterday (September 26).
Officers arrived with paramedics and treated a 62-year-old man but he was pronounced dead at the scene.
A 43-year-old man was arrested on suspicion of murder and taken to custody, where he remains.
Detective Inspector Richard Kempshall, who is leading the investigation, said: “My team are working at pace to establish the full circumstances that led to this man’s tragic death.
“We have arrested a man and no other suspects are being sought at this time.
“However, we are urging anyone who may have been in the area of Cowley High Street to look at any doorbell or camera footage and share anything that may be of use with police.”
This can be shared and uploaded online or by calling 101