The FCH JU strategy has identified hydrogen production by water decomposition pathways powered by renewables such as solar energy to be a major component for sustainable and carbon-free hydrogen supply. Solar-powered thermo-chemical cycles are capable to directly transfer concentrated sunlight into chemical energy by a series of chemical and electrochemical reactions, and of these cycles, hybrid-sulphur (HyS) cycle was identified as the most promising one.The challenges in HyS remain mostly in dealing with materials (electrolyser, concentrator, acid decomposer/cracker and plant components) and with the whole process flowsheet optimization, tailored to specific solar input and plant site location. With recent technology level at large-scale hydrogen production concepts hydrogen costs are unlikely to go below 3.0-3.5 €/kg. For smaller scale plant, the costs of hydrogen might be substantially higher.The present proposal focuses on applied, bottle-necks solving, materials research and development and demonstration of the relevant-scale key components of the solar-powered, CO2-free hybrid water splitting cycles, complemented by their advanced modeling and process simulation including conditions and site-specific technical-economical assessment optimization, quantification and benchmarking. For the short-term integration of solar-power sources with new Outotec Open Cycle will be performed. Simplified structure, extra revenues from acid sales and highly efficient co-use of the existing plants may drop hydrogen costs by about 50-75% vs. traditional process designs.Besides providing key materials and process solutions, for the first time the whole production chain and flowsheet will be connected with multi-objective design and optimization algorithms ultimately leading to hydrogen plants and technology “green concepts” commercialization.The consortium consists of key materials suppliers and process development SME and industry, RTD performers and a university.