Higher-order sliding mode control algorithms and second-order in particular have become a popular research area. This research analyzes the performance of optimally designed Super-Twisting (STW) controllers, with application to the liquid level process. The problem of optimal design of the STW controller is formulated and a solution methodology is presented. Performance of the STW controller is compared with the performance of an optimally tuned PID controller. The study is carried out through analytical approach, simulations and experiments. From the comparison of performance, conclusions are drawn about suitability and the use of the STW controller for the process specifically considered in this research as well as other process control applications.