DesignIt was the first attempt at a practical application of the ramjet technology that had been developed in the 0.10 and 0.21 research aircraft over the previous years. Unlike all previous Leduc aircraft, it featured swept wings and a coaxial turbojet-ramjet powerplant to enable unassisted operation.

Test flightsFirst flown on 26 December 1956 on turbojet power alone, the ramjet was finally fired on the 34th flight, on 18 May 1957. Another 80 flights took place before the cancellation of the project in favour of the more conventional Dassault Mirage III. A second prototype was under construction at the time.

End of operationsAlthough intended to be a supersonic fighter, the 0.22 proved unable to exceed the speed of sound (Mach 1) because of the prohibitive drag induced by its non-area-ruled fuselage at near-sonic speeds. The cancellation of the project marked the end of René Leduc's aircraft development activities.