On March 29, police say the suspect held up a Petro-Canada gas station on St-Charles West in the Old Longueuil borough.
They say the man was armed with a gun, and emptied the cash register before fleeing.
He left the Petro-Canada in a taxi and went to the Longueuil metro.
Police describe the man as white and in his 40s. He's five-foot-nine and around 175 pounds. His hair is chestnut, and at the time of the robbery, police say he wore blue jeans, a grey coat, and white shoes.
Police are asking anyone with information relating to the whereabouts of this suspect to call 1-800-711-1800.