Gatineau is a city in southwestern Quebec, Canada. It is located on the northern bank of the Ottawa River, immediately across from Ottawa, …Gatineau is a city in southwestern Quebec, Canada. It is located on the northern bank of the Ottawa River, immediately across from Ottawa, Ontario. Gatineau is the largest city in the Outaouais administrative region of Quebec and is also part of Canada's National Capital Region. As of 2021, Gatineau is the fourth-largest city in Quebec with a population of 291,041, and it is part of the Ottawa-Gatineau census metropolitan area with a population of 1,488,307 making it the fourth largest in Canada.