Separate fires have damaged buildings at Tighes Hill TAFE and near Hunter Trade College at Telarah overnight.
The fire at Tighes Hill saw a second floor administration room go up in flames at about 8:15pm.
Firefighters worked for three hours to ensure the fire didn't spread.
Classes in Building D have been disrupted today.
While the Telarah fire, which broke out at 8:20pm, caused a demountable building to suffer major damage.
"Firefighters mounted an aggressive internal attack and were successful in containing the fire to a number of offices," Fire and Rescue duty commander Paul Collis said.
"It was a very hot and difficult fire and the firefighters did an exceptional job."
The building is used by GE Power as a service centre.
Hunter Trade College says it's "open and operational."
Investigations are underway into both fires.