ABSTRACT:   This paper deals with the analysis of dynamic behavior of an electrohydraulic proportional actuator. The studied system consists of an electromagnetic proportional solenoid, a hydraulic cylinder and a directional control valve incorporating a non-conventional hydraulic amplifier. The spool of the directional control valve is driven by the pressure force developed by the built-in hydraulic amplifier. The peculiarity of the spool-solenoid interaction, forces the spool to have the same displacement as that of the solenoid core. The solenoid force is only needed to activate the hydraulic amplifies. This leads to the use of a solenoid of small dimensions. The system has been studied theoretically by deducing a nonlinear mathematical model, and developing a computer simulation program. The used solenoid is of the stroke controlled type. The steady state current-displacement relation has been measured and considered in the simulation program. The transient response of the solenoid has been measured experimentally and used to validate the simulation program. The proportional actuator has been studied in a closed loop control system. A PIC controlled has been designed to improve the closed loop dynamics. The performance of the system has been studied theoretically on the base of the developed simulation program.