The Marcello-class submarines were designed as improved versions of the preceding Glauco class.

[1] For surface running, the boats were powered by two 1,800-brake-horsepower (1,342 kW) diesel engines, each driving one propeller shaft.

On the surface, the Marcello class had a range of 7,500 nmi (13,900 km; 8,600 mi) at 9.4 knots (17.4 km/h; 10.8 mph), submerged, they had a range of 120 nmi (220 km; 140 mi) at 3 knots (5.6 km/h; 3.5 mph).

[2] The boats were armed with eight internal 53.3 cm (21.0 in) torpedo tubes, four each in the bow and stern.

[1] It was sunk on 8 November 1940 by a combined effort from the destroyers HMCS Ottawa of the Royal Canadian Navy, and HMS Harvester of the Royal Navy after attacking Convoy HX 84 they were defending.