Three Do Xs were constructed in total: the original operated by Dornier, and two other machines based on orders from Italy – the X2, named Umberto Maddalena (registered I-REDI), and X3, named Alessandro Guidoni (registered I-ABBN). The Italian variants were essentially identical to the original with the exception of being slightly larger and using a different powerplant and engine mounts. Dornier claimed the X2 was the largest aircraft in the world at that time. Each was powered by Fiat A-22R V12 water-cooled engines, with the six engine mounts being covered by a streamlined fairing. The Do X2 entered service in August 1931, and the X3 followed in May, 1932. Both were initially based at the seaplane station at La Spezia, on the Ligurian Sea, and reassigned to various other bases during their service.