An actuating device includes an exhaust flap of a supercharging pressure control of turbocharged internal combustion engines. The exhaust flap is arranged pivotably in an exhaust pipe, in particular in the housing of a turbine of an exhaust-gas turbocharger, and controls in dependence on the compressor-side supercharging pressure the opening cross section of a bypass line which circumvents the turbine. The exhaust flap is arranged on an actuator arm which is fastened on a shaft mounted rotatably in the exhaust pipe and adjustable from outside the exhaust pipe via an adjustment lever and a control rod which is articulated thereto and via a linear control motor. In order to avoid vibration-induced buzzing noise in the actuating device, a friction damper is connected into the force flow between the shaft and the control rod, in particular for system damping in the region of the exhaust flap.