technological progress affects the LCOH2. Furthermore, this methodology can be used to determine which progress is required to reach cost-competitive hydrogen production. It is inspired by the previous use of Monte Carlo for uncertainty quantification, and the use of contour plots to study how simultaneous change of multiple parameters impacts the LCOH2. 3. Application of this methodology to PV+E, PEC and PC, determining for each how much and which technological progress is needed produce hydrogen at a cost-competitive level. These insights are then used to derive actionable research targets for each technology.