Residents have reported seeing plumes of smoke coming from Heath Town Swimming Baths, a disused Grade II listed building.
West Midlands Fire Service currently has five appliances attending the incident on Tudor Road in Heath Town, Wolverhampton.
The first reports of the fire were made at around 7pm on Thursday evening.
A driver who was passing along Bushbury Road reported seeing multiple fire engines and lots of black smoke.
Heath Town Swimming Baths and Library has been closed and the building unused since 2003.
Last year, plans to turn the dilapidated former swimming pool into a major conference, wedding and banqueting were unveiled.
Sitting empty since 2003, the council-owned property has become a regular target for vandals and potential looters.