Sliding mode control (SMC) was first proposed for variable structures in the early 1950s in the former Soviet Union [1– ۳]. Since then, variable structure systems and their control methods have been used in a broad range of different applications, such as non-linear discrete models; and multiinput/multi-output, large scale, and stochastic systems. The main control goal for variable structure systems is to improve the closed-loop stability. In recent years, nonlinear controllers have been largely replaced by linear controllers for DC-DC power converters, using feedback linearization [4], adaptive back stepping control [5], non-active based control [6], and SMC [7] to regulate the output voltage. Robust SMC has attracted consider-able attention because of the simplicity of implementation, relatively low volume calculations, and the controller can be practically implemented using basic analog circuits rather than digital processors. Applying sufficient controller power switches, the power converter is tuned so the output voltage tracks the reference value (Vref). The effects of parasitic elements were not considered in the modeling phase. For example, the voltage drop across the power switch, semiconductor diode, and output capacitor equivalent series resistance in dynamic and steady state equations governing the behavior of the converter were neglected. The proposed method was simulated in MATLAB / Simulink, and the controller, buck converter, boost, buck/boost, and fly back responses were determined. The proposed sliding mode control can cover the operating range of load variations, input voltage, and other parameters to provide robust and steady output voltage.