ABSTRACT: Nowadays, the hydro-gas suspension unit is currently used as a part of suspension system of modern vehicles. This paper aims to evaluate the working characteristics of hydro-gas suspension unit. The theoretical study includes modeling of the hydro gas suspension unit and validation of the developed model using MATLAB/SIMULINK. The experimental measurements are carried out to validate the results obtained from simulation. The unit force, created inside the hydro gas unit during its action, includes the elastic and damping forces and Variation of these forces with displacement and velocity of moving part. This variation is used as input parameters in the equation of oscillation of vehicle hull to study its vibrational response. The obtained results show that the unit force depends mainly on the displacement and velocity of moving parts of hydro-gas unit. In addition, the results show that the effect of amplitude and frequency at small working range has a negligible influence on the unit force.