In March 1937, the Chance-Vought company, then part of United Aircraft Corporation, obtained an order from the US Navy to design a catapult reconnaissance-spotter float plane to replace the obsolete Curtiss SOC biplane. A year later, in March 1938, the first prototype XOS2U-1 took to the air in a version with non-retractable landing gear, and two months later the first takeoff from water took place.
Due to new technology, the prototype showed a considerable improvement in its main performance characteristics compared with its predecessor. It had longer range, a higher service ceiling and a considerably lower takeoff weight. In spite of the fact that a less powerful and lighter engine had been selected, the speed was unchanged and the mean rate of climb was even somewhat higher.
However, the more up-to-date design of the monoplane caused the designers a few headaches. By comparison with the SOC, its takeoff and landing characteristics were considerably worse. They had to give up on a central float designed by Vought itself and use an EDO design instead. After several minor improvements, the aircraft was put into series production and accepted by the Navy under the designation “Kingfisher” (the name of a tiny bird which lives on small lake fish). The production aircraft were fitted with the Pratt & Whitney R-985-48 “Wasp Junior” engine, nominal power 450 h.p., with a two-bladed propeller.
Up to the end of 1940, 54 OS2U-1s had been built, 18 of which were sent to re-equip battleships based at Pearl Harbor and Alameda.