The Bunsen reaction, as a part of the sulfur-iodine thermochemical cycle, was studied using an electrochemical cell. The effects of current density, operating temperature, H2SO4 concentration in the anolyte, HI concentration and I-2/HI molar ratio in the catholyte were explored. Both the H2SO4 in anolyte and the HI in catholyte were concentrated during electrolysis. Increasing current density amplified this H2SO4 and HI concentration, while the other operating parameters also varied the anolyte and catholyte concentration. The transport properties of the cation exchange membrane were examined. The electrode current efficiency remained close to 100% for most runs except those at high current density. Both the average cell voltage and the heat equivalent of electric energy were determined at different conditions. Crown Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.