The strategic goal of the ELYntegration Project is the design and engineering of a robust, flexible, efficient and costcompetitive single stack Multimegawatt High Pressure Alkaline Water Electrolysis (MW HP AWE) of 4,5 T H2/day capable to provide cutting-edge operational capabilities under highly dynamic power supplies expected in the frame of generation/ transmission/ distribution scenarios integrating high renewable energies shares. The final design of the MW HP AWE will be achieved on the basis of the development, validation and demonstration of a HP AWE industrial prototype of 250 kW (250 HP AWE) (TRL 7) comprising:- cylindrical stack consisting of industrial size elementary cells (1,600 mm cell diameter)- balance of plant - power electronics- advanced communication & control system In the early phase of the development process, great attention will be brought to the identification of enduser’s needs and relevant/critical operational requirements.The target behaviour of the industrial prototype will be thoroughly demonstrated in an operational environment reflecting different on-grid integration schemes using power facilities already available to the Consortium (notably, 635 kW wind and 100 kW photovoltaic power plants).As previously mentioned, the successful demonstration of the industrial prototype will be paving the way towards the implementation and the commercial deployment of the 4.5 T H2/day HP AWE technology in the frame of large scale demonstration projects which shall be the next step after the conclusion of ELYntegration.