Originally designed for the Central and South Atlantic passenger routes, it was later adapted as a military transport and special raider.

The design for the construction of a large four-engine, twin-float seaplane began at the end of September 1937, when the technical department of CRDA accepted the specifications of the LATI (Compagnia Ala Littoria) company, created in 1939[clarification needed], who required a long-range seaplane for carrying mail, cargo and passengers to Latin America.

The original engines were relatively underpowered, so Zappata asked the authorities for permission to acquire 1,193 kW (1,600 hp) Wright R-2600 Double Cyclones from the United States.

Between 28 February and 1 March 1942, test pilot Mario Stoppani succeeded in taking off and landing fully loaded in very rough seas, with 1.5 m (4.9 ft) waves and winds of 55–65 kilometres per hour (30–35 kn; 34–40 mph).

The Z.511 prototype was then transported to Grado, Venezia (further away from the insecure Yugoslavian border) for further evaluations; the last test and operational flight occurred on 1 September 1943, two days before the Italian Armistice was signed.