The leaking fluid created a white, odorless haze inside the plane that frightened passengers, CBC News reported.
The vapor appeared about 5 minutes after the Sunwing aircraft departed Macdonald-Cartier International Airport. The pilot of the Boeing 737-800 turned the plane and headed back to the Ottawa airport, Sunwing said in a statement.
About 170 passengers were aboard.
Paramedics were alerted at 6:40 a.m. and the plane landed safely at 6:53 a.m., authorities dais.
Firefighters said the vapor disappeared about 2 minutes after the plane landed. There was no fire and no one was injured.
Passengers departed on a second plane about 12:35 p.m.