C1 (upgraded on 26 January 1931) called for a single-seat fighter powered by a supercharged engine with a cylinder capacity of between 26 and 30 L (1,586.62 and 1,830.71 cu in).

The M.S.325 was relatively modest in its concept still featuring an open cockpit (originally the tail surfaces were fabric covered) and fixed-gear with the semi-elliptical two-spar wings braced by exterior struts.

4120) was flown for the first time by company Chief Test Pilot Michael Détroyat early in 1933 from the factory site at Villacoublay.

The first test results were not satisfactory as tail buffeting was encountered leading to modifications that included lowering the tailplane and adding wing root fairings.

Development based around a Hispano-Suiza 12Xers engine with a 20 mm (0.787 in) cannon was proposed but eventually, the M.S.325 design was abandoned in favour of the more promising M.S.405 C.1 with only partial performance tests completed.