In chemical cycles to produce hydrogen, the H2S splitting cycle and the sulfur-iodine (S-I) water splitting cycle both share the Bunsen reaction and HI decomposition. Therefore, they have to overcome the same challenges in the technology development, one of them being the complex and difficult separations of the mixed hydroiodic acid and sulfuric acid solution after the Bunsen reaction. To avoid the separations, this paper studies the electrolysis of the HI/H2SO4/H2O/toluene mixture, focusing on the electrochemical characterization of the Pt electrode by using linear sweep voltammetry (LSV) and cyclic voltammetry (CV). The results show that hydrogen is identified from the gas generated from the cathode in electrolysis. Iodide oxidation is the main reaction in the anode chamber and no significant side reactions are observed. Iodine deposition on the anode surface increases the resistance to iodide diffusion to the anode. However, it can be mitigated by adding toluene in or applying stirring to the anolyte HI/H2SO4 solution. The Pt cathode and sulfuric acid catholyte also work stably. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.