The project aims at developing a preliminary design concept together with experimentally validated analysis tools for the coupled hydro-aero-elastic analysis of multi-purpose floating platforms suitable for the offshore wind and wave energy resources exploitation. Hereby, Wind Turbines (W/T) will be used for capturing the wind field, whereas Oscillating Water Column (OWC) devices are foreseen for the wave energy exploitation. The numerical tools will be implemented to the preliminary design of a floating structure configuration suitable to operate at water depths of approximately 200m in the Aegean Sea. A representative but not exclusive configuration of the type of floating energy conversion systems we are looking for consists of a triangular platform supported by cylindrical floaters with the W/T mounted at deck’s center and the cylindrical OWC devices at its corners. Wind power is foreseen to be captured be W/T of either horizontal or vertical axes. The OWC consists of two concentric cylinders, with the water entering through the subsurface opening into the annular chamber between the two cylinders that contains air. The wave action causes the captured water column to rise and fall like a piston, compressing and decompressing the air. As a result, there is an air flow moving back and forth through a turbine coupled to an electric generator. The floater is moored with vertical tensioned tendons (TLP type mooring).