The physical model of an electrohydraulic actuation system has been obtained. To arrive at the closure of the model, experimental models for actuator friction and the characteristics of the proportional valves have been constructed. The variation of discharge through the proportional valve has shown the metered ports to be nonmatched that has been taken care of by estimating two separate coefficients for the main flow path and one leakage coefficient. An algebraic friction model retaining all the features of the existing differential model has been developed. All these nonlinear subsystem models have been integrated together in MATLAB/SIMULINK frame to predict the actuation dynamics. The variations of the predicted and experimental displacements of the piston against different command signals have been found to be quite close to each other.