This presentation reports long-duration durability testing of reinforced PFSA membranes for PEM water electrolysis (WE) under application-relevant conditions. Two prototype concepts were evaluated using multiple key performance indicators, including voltage decay, hydrogen crossover (H₂-in-O₂), and fluoride release rate, supported by in situ monitoring and post-test diagnostics.

An 85 µm membrane demonstrated stable operation over 28,000 h at 55 °C and 3.3 A cm⁻² with a voltage decay of 1.9 µV h⁻¹ , while a thinner 50 µm membrane achieved 1.2 µV h⁻¹ over 11,000 h at 20 bar differential pressure, maintaining low crossover and chemical degradation. Both prototypes meet or exceeded international targets for voltage stability achieving low degradation rates (<1%/year to <0.6%/year). Understanding key degradation mechanisms in PEM WE additionally enables improved chemical and crossover durability. Overall, the results provide quantified insights into durability-performance trade-offs and their implications for scaling PEMWE toward longer operational lifetimes, improved efficiency, and reduced operational costs accelerating the global transition to clean energy.