Police say the theft was reported July 21, but believe the art work by Cecilia Lueza entitled Landing was taken weeks earlier from the facility on East Franklin Street.
The museum closed to the public July 11 - after a 14-year run - because of financial problems.
The sculpture is made of urethane and is a large bright orange and yellow image of a girl in a dress and striped stockings jumping.
The Chapel Hill Public Arts office is offering $250 for the return of the sculpture no questions asked.
Call 968-2749, 968-2750, or email firstname.lastname@example.org