Solutions for large-scale and sustainable hydrogen production are urgently required, as hydrogen has the potential to decarbonize key industrial sectors and energy production. Solid oxide electrolysis (SOEL), unlike other green hydrogen generation methods, has unrivaled conversion efficiency. However, cutting-edge SOEL systems are incompatible with low-cost manufacturing techniques capable of producing electrochemical cells on a large scale. Furthermore, they are unable to produce hydrogen at a sufficient rate and cost. In this respect, the EU-funded OUTFOX project aims to overcome scale as a barrier to SOEL technology deployment while demonstrating its potential to become the preferred alternative for green hydrogen production. The industrially driven OUTFOX partnership aims to improve SOEL maturity and help the Clean Hydrogen Joint Undertaking meet its goals by integrating expertise in cell, stack, and module research, manufacture, and whole system evaluation. With cells that are 25% thinner than the existing state-of-the-art, OUTFOX will be able to achieve current densities of at least 0.85 A/cm2, boosting sustainability by reducing overall material requirements. The partners will use single repeating units, short stacks of 15 cells, and 80 kW prototype systems to test high current density operation at reference scale (144 cm2), industrial scale (>300 cm2), and next-generation cells (900 cm2). This will total more than 10,000 hours of SOEL operation. Finally, two 80 kW testing sessions with two separate stack configurations will be conducted over a total of 4000 hours of operation to thoroughly validate the OUTFOX technology. OUTFOX will prepare SOEL for industrial scale systems of 100 MW or more with an LCOH as low as €2.7/kg hydrogen by combining optimal cell and system designs with testing findings up to 80 kW scales.