Abstract: Metering device (10) for metering liquid media is described comprising a valve element (24) and a valve seat (22) allocated to the valve element (24). The valve element (24) blocks an opening (20) allocated to the valve seat (22) in a closed position of the metering device (10), through said opening (22) the liquid medium flows in an open position of the metering device (10). The metering device (10) includes a membrane (28) serving as an actuator (26) that is designed rigidly flexibly and is coupled to the valve element (24) in order to adjust the valve element (24). The membrane (28) comprises at least partially a structuring (34). The metering device (10) includes a pneumatic actuator unit (14) so that the membrane (28) serving as an actuator (26) is operated pneumatically, wherein the membrane (28) is sealed against the medium to be metered. Moreover, a method for metering liquid media is described.