The present invention provides a method for emptying a reactor containing at least one bed of spent catalyst particles, wherein the reactor comprises at least one dump tube that opens into the reactor. The method comprising the steps of: (a) causing a portion of the bed of spent catalyst particles to flow out of the reactor via the dump tube; and (b) extracting the remainder of the spent catalyst particles from the reactor by driving the remainder of the spent catalyst particles toward the opening of the dump tube using a removable device comprising at least one flexible extraction sleeve introduced into the reactor via the said dump tube and connected to an extraction system situated outside the reactor, the sleeve being provided on its external surface with protuberances and being able to move, inside the reactor, translationally and rotationally with respect to the dump tube.