Optical lighting equipment used for sensory development was stolen from a shed at Stainforth Children's Centre, Junction Road, Stainforth, between 6.30pm on Monday, May 7 and 7am the following morning.
Details of the break-in have only been released today by South Yorkshire Police in a bid to trace the offender.
A force spokeswoman said: "The optical lighting equipment, which was taken from the shed, is of great benefit to those who use it on a regular basis and officers in Doncaster are asking if you have any information about what happened.
"CCTV enquiries have been carried out in the area as well as enquiries within the community, but so far officers have been unable to reunite the centre with the equipment.
"Do you know anything about what happened?"
Anyone with information should call South Yorkshire Police on 101.