Hydrogen has the potential to provide a reliable, secure, and clean source of power. The barrier is the challenge of getting hydrogen economically to the point of use. Water electrolyser offers a practical way of hydrogen production in association with renewable energy sources. Compared to the conventional alkaline electrolyte electrolyser, the polymer electrolyte membrane (PEM) electrolyser can operate at high current densities and pressure with compact design. The main challenges for PEM electrolysers are high capital cost of key materials, components and the overall system as well as insufficient long-term durability. The strategic development of the WELTEMP project is an elevated operating temperature of the PEM electrolyser. In this way the energy efficiency will be significantly improved because of the decreased thermodynamic energy requirement, enhanced electrode kinetics, and the possible integration of the heat recovery. Key issues to achieve this strategic target are breakthroughs of fundamental materials developments, including catalysts, membranes, current collectors, bipolar plates, and other construction materials. The WELTEMP will start with developing active and stable anodic catalysts based on mixed metal oxides, temperature-resistant PEM based on composite PFSA, sulfonated aromatic and/or acid-base cross-linked polymers, and highly conducting and corrosion-resistant tantalum thin surface coatings as current collectors and bipolar plates. Based on these materials, a 1 kW prototype electrolyser will be constructed for demonstration and evaluation. It is aimed to reach operational temperature above 120C and a hydrogen production of 320 NL/h at 80% efficiency (LHV basis) at system level. These innovative developments need trans-national efforts from European industries and R&D groups. The expertise and know-how of the consortium in the field of refractory metals, electrocatalysts, polymers and membranes, MEA fabrication, and most importantly the constr