The M11/39 was the first M series tank built for the Italian Army. The first prototype was completed in 1937 and the vehicle was accepted for service in the following year. The vehicle was armed with a limited traverse 37/40 gun mounted in the right side and two 8mm Breda machine-guns mounted in a turret that provided a 360 degree field of fire.

Manned by three man crew; a commander/turret gunner, gunner for the 37/40 gun and a driver, the M11/39 was powered by a 125HP Fiat V8 diesel engine. Protection for the crew was provided by armor plate up to 30mm thick that was either bolted or riveted onto the steel frame of the vehicle. The vehicle was also fitted with a number of pistol ports, allowing the crew to fire their sidearm's from inside the tank if enemy infantry go to close.

The M11/39 first saw action with the Italian Army in July 1940 after being deployed in Libya. However, the tactics used to employ the vehicles in action were questionable at best and the shortcoming of the tank soon became apparent on the battlefield; mainly due to the lack of an onboard radio and the hull mounted 37/40 gun. A number of these vehicles were captured by British and Commonwealth forces and used by the 6th Divisional Cavalry Regiment.