A copper chloride (CuCl) electrolyzer that constitutes of composite proton exchange membrane (PEM) that functions at medium-temperature (>100 degrees C) is beneficial for rapid electrochemical kinetics, and better in handling fuel pollutants. A synthesized polybenzimidazole (PBI) composite membrane from the addition of ZrO2 followed with phosphoric acid (PA) is suggested to overcome the main issues in CuCl electrolysis, including the copper diffusion and proton conductivity. PBI/ZrP properties improved significantly with enhanced proton conductivity (3 fold of pristine PBI, 50% of Nafion 117), superior thermal stability (>600 degrees C), good mechanical strength (85.17 MPa), reasonable Cu permeability (7.9 x 10(-7)) and high ionic exchange capacity (3.2 x 10(-3) mol g(-1)). Hydrogen produced at 0.5 A cm(-2) (115 degrees C) for PBI/ZrP and Nafion 117 was 3.27 cm(3) min(-1) and 1.85 cm(3) min(-1), respectively. The CuCl electrolyzer efficiency was ranging from 91 to 97%, thus proven that the hybrid PBI/ZrP membrane can be a promising and cheaper alternative to Nafion membrane. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.