The MRAC is applied to the control of an electrohydraulic system controlled by a solenoid valve. The adaptive algorithms proposed in this paper guarantee the asymptotic stability of the error between the plant output and that of the reference model. The robustness properties of the adaptive control system are examined based on the concept of a tuned system—an ideal converged (non-adaptive) closed-loop system when the gain of the valve is varying non-linearly. A modified adaptive law that guarantees the tracking error will be bounded in a residual region is proposed. The performance improvement is also studied by implementing the ternary mode solenoid valve. To illustrate the validity, the simulation results of a gun turret position control system are also included.