This happened at about 5:01 a.m. in the 5900-block of South Ashland in the Englewood neighborhood.
The 7th District officers were in a marked squad car when police said someone in another vehicle approached them and sprayed into the squad car.
The officers inhaled the fumes, police said. They were both treated and released on the scene.
According to U.S. Poison Control, exposure to fire extinguisher fumes can cause risk for mild respiratory, skin or eye irritation. Inhaling fumes can produce serious toxicity and would require medical evaluation.
No one is in custody as detectives investigate the incident.