The substances involved in the sulfur-iodine (SI) thermochemical cycle to produce H-2 by water splitting are very corrosive and may attack reactors, pumps, catalysts supports, and whatever part of the plant. This paper investigates the corrosion exerted by HI solutions in liquid, boiling, and gaseous phase at different temperatures. It shows the broadest over- view of the behavior of different materials, ranging from pure metals to metallic alloys, from carbon materials to organic polymers, from ceramic materials to composite ones. Commercial nickel alloys and the effect of a specific element in their composition have here considerable attention. Regarding the composites materials, the impact of the sub- strate as well as the coating nature and thickness is studied, also through SEM-EDS (Scan Electron Microscope Energy Dispersive Spectroscopy) investigations. Carbon materials performed well, while most of the analyzed materials showed inter-granular corrosion, pitting phenomena, and sometimes, carbide precipitation in the higher energy zones. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.