Hydrogen gas generation from water in the temperature range of 10-60 degrees C using iron and carbon dioxide was studied. During the reaction, carbon dioxide consumption and hydrogen generation were observed, and the stoichiometry of the redox reaction with iron carbonation was checked. The rate of the reaction steadily increased with the temperature, and the time required to consume half of the carbon dioxide at 60 degrees C was less than one-fifth of that at 10 degrees C. The activation energy was determined by examining the temperature dependence of the reaction rate. Carbon dioxide used in the reaction precipitated as carbonate in the aqueous phase, covering the raw material iron and hindering the progress of hydrogen generation reaction. Experiments following the same procedure were performed using steel and sludge from steel processing, which contained elements other than iron, to show that hydrogen generation and carbon dioxide fixation were also possible. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.