The thesis project is oriented to the ISWEC (Inertial Sea Wave Energy Converter). The ISWEC is an electrical system that converts the incident wave power into electrical energy. The basic work principle is to use the gyroscopic effect in order to take in motion a shaft connected to a PTO unit(Power Take Off), so damping such rotation with a proper torque the electrical energy is obtained. The main goal is to find a controller through the Robust Control approach with H-inf techniques, based on reference tracking error, such that the produced power is comparable to the previous MPC controller, that presents optimal conversion energy but high computational requirements.