Midcourse guidance plays a crucial role in long range air-defence interception missions by guiding the interceptor from the launch site to the vicinity of the target, allowing the onboard seeker to lock onto the target, and facilitating successful interception during the terminal phase. In recent years, the demand for advanced optimal guidance techniques has surged in response to the development of new classes of targets characterized by high maneuverability and hypersonic speed, leading to increased uncertainty in predicting the impact point. The thesis aims to formulate and implement an online guidance algorithm that addresses the challenges posed by these new targets.