Police and fire crews have launched an investigation after a blaze at the former Harris Academy building on Perth Road.
A caretaker at the building raised the alarm shortly before 9pm on Sunday after spotting a fire in a first-floor classroom.
Fire crews from three Dundee stations rushed to contain the blaze, which had by then spread to the second floor of the building.
A fire and rescue spokeswoman said: “We had three jets and six breathing apparatus in attendance from Blackness Road, Kingsway East and Macalpine Road along with thermal imaging.”
The blaze was quickly extinguished but the crews remained on site checking for hotspots in the building.
Harris Academy pupils have moved to the old Rockwell High School while the Perth Road building is knocked down and rebuilt in a £31 million renovation expected to last three years.