In this paper, an extended sliding mode control (SMC) method is proposed for applications to general class of control systems. The proposed method is based on lower order models obtained from slow or fast dynamical systems. In the proposed method, the sliding mode controllers (SMCr) are designed based on the three term controller (PID) with first order filter sliding surface. The motivation for the proposed work in this paper is that the methodology adopted for controller design is applicable to general unknown class of SISO systems. This systems having lower or higher order dynamics, oscillatory or monotonic behavior and with or without time delay. The performance of designed controller is excellent for variation in parametric and unmodeled uncertainty in the system. The robust property of the proposed method is verified by applying an external load disturbances (fixed and variable). The stability and robustness of the proposed controller are investigated using Lyapunov stability theorem. The high frequency chattering phenomenon which commonly occurs in SMC controller, is significantly reduced by adopting the switching gain with the known parameters of the system. The performance of the proposed SM control method is validated with the help of simulation examples and results are compared with other control methods available in the literature.