Proton Exchange Membrane (PEM) electrolyzers can produce green hydrogen from water and renewable electricity. They also typically rely on one of the rarest materials on earth to function: iridium. To scale electrolyzer manufacturing to meet rising demand for clean energy, the hydrogen community must develop solutions to address this supply chain issue. Using technology developed at Caltech, H2U built a Catalyst Discovery Engine that can be used to rapidly make, characterize, and quantify the catalytic activity of materials. Leveraging this method, H2U has uncovered novel, non-iridium catalysts that have been validated both in-house and through third-party testing. H2U then synthesizes catalyst hits as nanoparticles, incorporates the particles into catalyst coated membranes (CCMs), and evaluates the resulting CCMs for performance and stability. This method of catalyst development, from high-throughput discovery through testing and evaluation under real PEM electrolyzer operating conditions, offers a promising path toward commercialization of novel materials for hydrogen production.