A 23-year-old man has been arrested on suspicion of robbing a Next store just before Christmas while dressed as Santa.
The man went into the staff section of the shop in Oxford Retail Park, Cowley.
He threatened a member of staff with a knife and demanded cash from the shop's safe.
Once this had been given to him the man then made off on a bicycle towards Blackbird Leys Bridge.
The man has been bailed until May 21 for the robbery which took place on December 23.
Anyone with information about the offence should contact Det Con Tom Mansfield at Thames Valley Police on 101 or, if you wish to remain anonymous, call Crimestoppers on 0800 555 111.
A cash reward is being offered for information about the incident.