Described is a propulsion system (1) for hypersonic aircraft, having an air inlet (10) of a fluid (110), a containment duct (20) and an exhaust nozzle (30). The propulsion system (1) comprises a bypass duct (40) for a flow (100) of fluid (110), an air-breathing engine (22) and a rocket (23) configured for processing respective flows (22a, 23a) of fluid (110). The bypass duct (40), the air-breathing engine (22) and the rocket (23) are operatively associated with each other in such a way as to generate a thermodynamic-fluid interaction in a same portion of space (33) between the respective flows (40a, 22a, 23a) processed in an operating configuration of the propulsion system (1) and wherein the portion of space (33) is inside the containment duct (20).