This paper presents adaptive Sliding Mode Control combined with an Extended Kalman Filter used as an observer to control metal-polymer composite fibers as an actuator. The mechanismus based on the characteristic of the thermoplastic polymer which is coated with silver particles. Usual the interface between the polymer and the silver surface connected by physical or chemical methods to promote strong interactions between metal and polymer. To control this actuator a sliding mode control (SMC) is combined with an Extended Kalman Filter (EKF) and used as an observer. Despite of the particular simplified model of the considered actuator the EKF presents a nonlinear Jacobian Matrix. The parameter setting of system and the measurement covariance matrix together with their initial values are done heuristically. The sliding mode control scheme is designed using the well known Lyapunov approach. The simulation results indicate that the proposed algorithm is effective and robust.