Metering valve for an aerosol container, having an internal face intended to be placed inside the aerosol container and an external face intended to be placed outside the aerosol container, said valve being provided with - a valve body having an internal chamber able to be put in contact either with the internal face of the valve or with the external face of the valve, - a stem provided with closure means and placed partly inside the internal chamber able to move between two positions, namely a closed position in which the internal chamber is in contact with the internal face of the valve, but isolated from the external face of the valve, and an open position in which the internal chamber is in contact with the external face of the valve but isolated from the internal face of the valve, - a reservoir able to be filled when the stem is in the closed position and emptied when the stem is in the open position, - the reservoir being situated on the side of the internal face of the valve, outside the valve body, - the reservoir being in contact with the internal chamber of the valve body, - the reservoir consisting of at least one flexible membrane and of a rigid wall on which the flexible membrane is fixed, - the face of the rigid wall directed towards the flexible membrane and/or the face of the flexible membrane directed towards the rigid wall having a cavity, - a communication channel being provided in the valve body for connecting the inside of the reservoir and the internal chamber, characterised in that. grooves are provided in the face of the rigid wall directed towards the flexible membrane and/or in the face of the flexible membrane directed towards the rigid wall, said grooves extending from the inlet of the communication channel in the direction of the peripheral edge of the cavity, and in that the various grooves diverge from the communication channel while forming a star. - a valve body having an internal chamber able to be put in contact either with the internal face of the valve or with the external face of the valve, - a stem provided with closure means and placed partly inside the internal chamber able to move between two positions, namely a closed position in which the internal chamber is in contact with the internal face of the valve, but isolated from the external face of the valve, and an open position in which the internal chamber is in contact with the external face of the valve but isolated from the internal face of the valve, - a reservoir able to be filled when the stem is in the closed position and emptied when the stem is in the open position, - the reservoir being situated on the side of the internal face of the valve, outside the valve body, - the reservoir being in contact with the internal chamber of the valve body, - the reservoir consisting of at least one flexible membrane and of a rigid wall on which the flexible membrane is fixed, - the face of the rigid wall directed towards the flexible membrane and/or the face of the flexible membrane directed towards the rigid wall having a cavity, - a communication channel being provided in the valve body for connecting the inside of the reservoir and the internal chamber,