Des Geneys was one of four s built for the (Royal Italian Navy) during the late 1920s. Due to her age, her usefulness was limited, and she saw no real service during World War II. The submarine was decommissioned in 1942 and converted into a battery-charging hulk.
Designed in parallel with the s, the Pisani class was larger accommodate more fuel and give them more range. They displaced surfaced and submerged. The submarines were long, had a beam of and a draft of . They had an operational diving depth of . Their crew numbered 48 officers and enlisted men.
For surface running, the boats were powered by two diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a electric motor. They could reach on the surface and underwater. On the surface, the Pisani class had a range of at ; submerged, they had a range of at .
The boats were armed with six torpedo tubes, four in the bow and two in the stern for which they carried a total of nine torpedoes. They were also armed with a single deck gun forward of the conning tower for combat on the surface. Their anti-aircraft armament consisted of two machine guns.
Des Geneys was laid down by Cantiere Navale Triestino in their Trieste shipyard on 1 February 1926, launched on 14 November 1928, and completed on 31 October 1929.