An electrically operated injector (1) for feeding a gaseous fuel to a cylinder of an internal combustion engine, in particular for a motor vehicle, includes an electromagnetic actuator (2) acting on a mechanical interceptor member (3) arranged to free or intercept a passage (4) for the fuel from a feed conduit (61) to a delivery conduit (5) connected to an outlet (6), between the delivery conduit (5) and the interceptor member (3) there being positioned a seal element (40). This latter is carried by the interceptor member (3) and has a shape tapering towards the delivery conduit (5) in order to effectively intercept the fuel gas passage (4) and minimize the area of impact with an annular end portion (43) of the delivery conduit (5).