A university spokesperson says the fire started when liquid metal came into contact with flammable material in a metallurgy lab.
When 30 firefighters arrived at the scene, security guards were fighting the blaze with fire extinguishers.
After determining that the chemical fire could be safely extinguished with water, firefighters finished the job.
Approximately 3,000 people had to leave the campus.
The university says there were no injuries.
The evacuation order was lifted around 3:15 p.m., roughly one hour after the fire began.
Investigators from Quebec's Commissariat des incendies are still trying determine the exact cause of the incident.