An adaptive pole placement controller with dual modification is applied to a dynamic plant which is described by an unknown nonlinear model. Stability of the suggested dual controller, applied together with a robust adaptation scheme, is proved for this system. It is demonstrated that after the insertion of the dual controller, the robust adaptive system remains stable. However, some known assumptions about the unmodelled residuals of the nonlinear plant model should be modified. It is also demonstrated that in the case of no residuals in the plant model, the closed-loop system converges to the model defined by the desired pole positioning. The derived controller is applied to real-time control of hydraulic drive.