The submarine "Platino" was a part of a class of coastal submarines formed by 13 units, denominated Acciaio or Platino, which entered service when the war had already started. The units were built in La Spezia by the OTO shipyards (four units), in Montefalcone by the CRDA shipyards (six units) and in Tarento by the Tosi shipyards (three units). These latter slightly differed from the others because the propulsion plant was fitted with two Tosi Diesel engines of 750 horsepower, instead of the Fiat of 700 horsepower, which increased the maximum speed in surface from 14 knots to 14.7 knots. Also the armament was increased, by increasing the number of torpedo tubes from six to eight. The silhouette of the submarines of this class was somewhat different to that which was usual in the Italian submarines, because it was preferred to adopt a smaller turret of oceanic type, similar to that of the German Type VII U-Boote. Also the silencing of the propulsion plant was improved, and a launching central of a more adequate type was installed. The units were later fitted with radio devices and radar localizators. Almost all of these units, of satisfying qualities, had a rather short life. Some of them were sunk in their first mission, and therefore it is not possible to make a fair estimation of their performance in respect of that of the former classes. During her operational life, the "Platino" sank a British escort unit, the corvette "Samphire", severely damaged a steamship and downed an anti-submarine fighter aircraft. At the arrival of the Armistice she went to Malta, due to the orders received, and her activity until the end of the conflict consisted of taking part in some exercises along with Allied units. Disarmed at the end of the war, she was scrapped the 1st February 1948. Another two units of the same class, the "Nichelio" and the "Giada", survived the war along with her. The first one, after being subjected to repairs, was delivered to the Soviet Union in 1949, and the second one, modernized more times, remained in service in the Marina Militare until the 1960s.