The Cu-Cl thermochemical cycle is among the most attractive technologies for hydrogen production due to its high efficiency and moderate temperature requirements. In this study, the H 2 producing reaction of the cycle, CuCl(aq) electrolysis, was investigated in a recently developed electrolyzer using a new type of double layer Nafion 117 membrane. Enhanced MEA durability allowed the system to operate at 80°C for an extended period of time with continuous anolyte cycling and regeneration. An applied potential of 0.7 V was needed to produce the current density of about 0.12 A/cm 2, and the system maintained performance over a period of 100 hours with no substantial decline of hydrogen production rates. Linear polarization and electrochemical impedance spectroscopy were used to monitor the electrolyzer performance over time. Further research is underway to optimize the process parameters and MEA fabrication to extend the electrolyzer life time and current density.