This thesis aims at designing a control-oriented model for the Inertial Sea Wave Energy Converter (ISWEC) system. The ISWEC system consists of a floating device composed by a hull which hosts a gyroscope system whose motion is induced by the pitching oscillations of the hull floating on the sea surface. Energy extraction is obtained by damping the gyroscope precession motion through an electrical Power Take Off (PTO) unit, which is implemented by an electric motor able to exert the torque intended for damping such a motion. The shaft, about which the precession motion takes place, is mechanically connected to the PTO shaft.