In this paper constant reference output tracking is achieved using second order sliding mode (SOSM) control. To achieve tracking a new sliding surface is proposed and to ensure sliding motion super-twisting control (STC) is employed. The proposed sliding surface is more general, and it can be used for constant reference tracking in both minimum phase and non-minimum phase systems. The proposed method is validated on the unstable non-minimum phase inverted pendulum system and also the results are compared with the first order sliding mode control (SMC) in simulation and experimentally both. © 2018 European Control Association