As with most French twin-engined aircraft of the era, the engines were handed, one airscrew rotating clockwise and the other anti-clockwise, to minimise torque.

The aircraft was fitted with four Hispano-Suiza HS.404 20 mm cannon in the nose and one in the gunner's post.

[1][2] The aircraft proved to be around 100 km/h faster than the Potez 631, the French Air Force's current twin-engined fighter, and production was authorised.

While the tests were proceeding, a second prototype was being built, incorporating the changes, the most obvious of which was the removal of the windowed corridor in the fuselage and its replacement by additional fuel tanks.

As the second prototype was being built, the Citroën company was preparing to mass-produce the aircraft at their Paris works, deliveries planned to begin late in 1940.