This paper presents the research concerns of Hydraulics and Pneumatics Research Institute in Bucharest in gaining knowledge about the specific phenomena and processes related to the operation of medium and high pressure actuators, in order to increase energy efficiency of pneumatic drive systems. At INOE 2000-IHP, in the Laboratory of Pneumatics have been conducted tests on the EM of a pneumatic system with medium and high pressure actuators. The following tests have been carried out upon it: the response of the pneumatic drive system with medium pressure actuator to step signal, for various values of the PID controller and controlled load, and there have been developed the next graphs: attenuation vs. frequency and phase vs. frequency (Bode plot).