The invention relates to a feed device for feeding a thrust chamber (10) of a rocket engine (100) with first and second propellants. According to the invention, a first feed circuit (16) of the thrust chamber (10) comprises a turbopump (22) having at least one pump (22a) for pumping the first propellant from a first tank (12), and a turbine (22b) mechanically coupled to said pump (22a). The first feed circuit connects an outlet of the pump to an inlet of the turbine via a heat exchanger (24) configured to heat the first propellant with heat generated by the thrust chamber, in order to actuate the turbine. According to the invention, a second feed circuit (18) is configured to feed the thrust chamber with second propellant from a second tank (14) that is configured to be pressurized. The invention also provides a method of feeding a rocket engine thrust chamber with first and second propellants.