The Ca.20 was derived from the Ca.18 an observation monoplane that had been developed starting in 1913 from the previous models Ca.8 and Ca.16. It used a more powerful engine, the Rhône. It used an unusual rounded nose cover for the wooden propeller which was cowled smoothly to match the fuselage. The cover was pierced to allow cooling of the engine. The improved aerodynamics helped speed and manoeuvrability. Designed as a fighter, a Lewis machine gun was installed above the pilot, placed above the propeller disc, with an eye level sight. The first synchronization devices, which allow a weapon to shoot with confidence through the blades of a propeller in motion, would not make their appearance until the Fokker Eindecker during 1915, although many experiments were conducted by the French since 1913.
Only a single Caproni Ca.20 was ever built, because the Italian government rejected the design in favor of bomber aircraft. The prototype was stored in a barn on Giovanni Battista Caproni's property for 85 years, before being sold to the Museum of Flight in Seattle in 1999. Luckily, the dry climate had preserved the aircraft. With the exception of the tires, which had been gnawed by rodents, the prototype Caproni Ca.20 on display at the Seattle Museum of Flight includes all its original parts.