Argo was the lead ship of her class of two submarines ordered by the Portuguese government, but taken over and completed for the Regia Marina (Royal Italian Navy) during the 1930s.

[2] For surface running, the boats were powered by two 750-brake-horsepower (559 kW) diesel engines, each driving one propeller shaft.

On the surface, the Argo class had a range of 10,176 nautical miles (18,846 km; 11,710 mi) at 8 knots (15 km/h; 9.2 mph); submerged, they had a range of 100 nmi (190 km; 120 mi) at 3 knots (5.6 km/h; 3.5 mph).

They were also armed with a single 100-millimeter (3.9 in) deck gun, forward of the conning tower, for combat on the surface.

[2] Argo was built by Cantieri Riuniti dell'Adriatico in its Monfalcone shipyard.