Water electrolyzer stacks are a key component of regenerative fuel cells, designed to replace batteries as a means of storing electric energy on the lunar surface. The design and demonstration of an innovative water electrolyzer cell is proposed. The cell design will be significantly smaller and lighter than previous aerospace electrolyzers designed and built by Giner Electrochemical Systems, LLC. The new cell will support high-efficiency electrolysis at pressures up to 2,000 psi. Test data will be used to calibrate electrolyzer performance models. These models will, in turn, be used to guide design decisions for regenerative fuel cells relative to the electrolyzer stack and maximum operating/gas-storage pressures of the regenerative fuel cell. A preliminary analysis of an advanced cell frame new thermoplastic material will be conducted to determine its suitability for use in water electrolyzers. Successful completion of the first phase will lead to the development of a demonstration stack in a second phase.