It was one of the many flying boats made by SIAI (Savoia-Marchetti), that in 1915 had started building foreign aircraft under licence, followed two years later by the first of its own designs.

The prototype, which carried the serial number MM222, made its first flight late in 1932[1] and then transferred the next year to Vigna di Valle for evaluation.

It had a long and slim aft fuselage, with a tall welded steel fin and a wooden horizontal tail mounted centrally.

This aircraft evolved from the SM.62bis, retaining practically the same unmodified wings, tail and fuselage, but with a different model of Handley Page flaps.

The fabric-covered wings had spruce longerons and poplar ribs, utilising the low-weight and high-strength characteristics of these woods, and were painted to render them impermeable to water.

A second, enclosed turret was fitted in the dorsal position, also armed with a 7.7 mm (.303 in) Lewis gun, manned by the gunner/radio operator, who was also provided with an R.A.350 transmitter and an A.R.4 receiver.

Some aircraft remained in service during the early phase of World War II, performing in an air-sea-rescue capacity.