The incident took place at the NatWest bank on School Road, around 11.45am, on Saturday 18 November.
The offender entered the bank and stole a large clear charity jar, which contained a quantity of cash, from the counter. The offender then ran out of the bank and handed the jar to a second offender.
The two offenders then ran in opposite directions along School Road.
The second offender, still carrying the jar, was chased by a member of the public along St Michael’s Road. The offender managed to escape through an alleyway on Keswick Close and was heading towards The Meadway.
The first offender is described as a white man, aged in his early twenties and wearing dark clothing.
The second offender is described as a white man, aged in his early twenties, of slim build and cropped black hair. He was wearing a hooded black coat with a red logo on the back close to the shoulders and loose dark navy blue tracksuit bottoms. The left leg was tucked into a red sock.
Investigating officer, PC Lincoln Houghton from Reading police station, said: “I am appealing for anyone who witnessed this incident to come forward.
“If you have any information relating to this theft, please call the Thames Valley Police non-emergency number on 101, quoting reference 43170343611. Alternatively, you can call Crimestoppers anonymously on 0800 555 111.”