Staffordshire Fire Service yesterday said the fire which saw Police shut off Elgood Lane in Goldenhill was deliberately started.
Crews from Kidsgrove and Sandyford fire stations were called at 3.36pm and extinguished the fire leaving at 4:50pm.
The fire was at a derelict school building, formerly Goldenhill Primary School in the grounds of St Johns church, and has been the target of numerous attacks over the years.
Anyone with any information is asked to contact Staffordshire Police on 101. Alternatively, they can ring independent charity Crimestoppers, anonymously, on 0800 555 111.