A design procedure of an active ride control system (RCS) for regulating the roll and pitch motions of a high speed marine vessel is presented. In order to achieve high quality passenger comfort and reduce the seasickness it is necessary to counterbalance the excessive pitch and roll motions using an active ride control system. To do so, a mathematical model of the vessel describing the motion of the high speed vessel in 3 degree of freedom, heave-roll-pitch, is derived using VERES (VEssel RESponse) program. The effect of active T-foils and interceptors is discussed, and a frequency weighted H2-optimal controller is designed and implemented. The performance of the proposed ride control system is shown by experimental tests of a scaled model of high speed catamaran in MARINTEK's ocean basin.