In order to combat the climate changes and to reach the European goals for reduction of greenhouse emissions, fossil fuels must be replaced with renewables. MegaSyn will contribute by upscaling high-temperature co-electrolysis to mega-watt scale to produce green syngas (CO + H2) out of renewable electricity, waste CO2 and H2O. This process is called Power-to-X; it is the most important approach to decarbonise hard-to-electrify sectors such as the iron and steel industry, the chemical industry as well as heavy and long-distance transport, as syngas can be used as precursor for the manufacture of e-fuels and other chemicals. By using the co-electrolyser technology, the highest overall process efficiencies can be achieved. MegaSyn will demonstrate that syngas can be produced via the solid oxide electrolyser cell technology (SOEC) in quantities relevant for industrial applications, while showing the way to competitive electrolyser costs and durability. It will be the world’s first demonstration of syngas production by co-electrolysis on the mega-watt scale in an industrial environment at the Schwechat Refinery in Austria. The project will lift the technology from TRL 5 to TRL 7, thus taking an important step towards commercialisation. The consortium is carefully selected to cover all the necessary competences: DTU and TU Graz, respectively, will improve knowledge on degradation of cells and stacks and purification needs of feed streams, while Sunfire will design & build the co-electrolyser; OMV will install it at their Schwechat Refinery and Paul Wurth will perform the engineering of overall system integration. After installation, the MegaSyn system will run for 2 years to demonstrate the production of >900 kg syngas based on renewable energy. Integrating the co-electrolyser based MegaSyn system at a refinery proves its value not only for the production of e-crude but also as a mega-watt scale system that can be integrated in e.g. the chemical industry.