This paper investigates the robustness with plant parameter variation of a sliding mode controller (SMC) that was recently proposed. Nonlinear chaotic systems are used as they are sensitive to parameter change and initial conditions. Synchronization of chaotic systems is used as it solves the tracking problem in a dynamic environment. The convergence time as a measure of robustness is also observed. Overall it is shown illustratively that the controller performs well but not as good as model free controller (MFC). The convergence and convergence time of the SMC, thus its robustness can be improved with an appropriate choice of the sliding surface. Simulation tests are conducted in MATLAB to support the study‥