An anaerobic propulsion device of hybrid type. The propulsion device includes a combustion chamber into which an oxidant is injected thereto comes into contact with a fuel. The chamber includes an orifice, notably a nozzle, to inject the combustion gases. The fuel takes the form of solids divided into granules, typically grains, powder or beads. The propulsion device further includes a segregation device arranged between a reservoir for granules of solid fuel, and the combustion chamber. The segregation device is configured to prevent granules of fuel in solid form from passing between the reservoir and the combustion chamber. The segregation device includes orifices to allow the passage of the fuel, once the fuel has become pasty, liquid or vaporized.