The Cu-Cl thermochemical cycle is among the most attractive technologies proposed for hydrogen production due to moderate temperature requirements and high efficiency. In the present study, one of the main steps of the cycle - H2 gas production via CuCl-HCl electrolysis - was investigated using a newly designed electrolyzer system. The electrolysis reaction was performed with the applied voltage from 0.35 to 0.9 V. The current efficiency of the electrolysis system was evaluated based on the observed rate of hydrogen production. The effects of temperature and reagent flow rate on the electrolysis performance were studied. Several types of anion-exchange and cation-exchange membranes were tested in the electrolyzer, and their performance was compared with respect to process efficiency and tolerance to copper crossover.