In this paper,a second-order sliding mode predictive guidance law is proposed for tracking maneuvering targets.The proposed guidance law utilizes the generalized model predictive control theory and the second-order sliding mode, which is developed to improve the tracking performance against targets with unknown maneuvers. In this method, by considering the target maneuvers as uncertain, there is no need to measure or estimate these maneuvers precisely which simplifies the guidance law. To determine the acceleration command of the interceptor, the slip surface is defined based on the line-of-sight rate. In addition, the second-order sliding surface is used to reduce the effects of the chattering phenomenon. The proposed method takes advantage of the advantages of predictive control, including predicting the future behavior of the system and simultaneously optimizing the performance. The effectiveness of the proposed guidance law has been investigated by performing numerical simulations and applying it to a ground-to-air interceptor for tracking targets without maneuvering and with step, sinusoidal and random maneuvers. The results of the developed guidance law have been compared with the performance of the first-order sliding mode predictive guidance law and it has been shown that the proposed method has a better performance in dealing with maneuvering targets.In order to investigate the feasibility of implementing this guidance law,processor-in-the-loop implementation has been done and the results obtained in real-time conditions have been presented. The results of this test confirm that the proposed guidance law, in addition to its better performance in numerical simulations, also has the capability of practical implementation.