The absorption between hydrogen isotopes and storage materials (ZrCo or uranium) is an exothermic reaction. The exothermic reaction characteristics upon the hydriding of hydrogen isotopes with ZrCo and depleted uranium (DU) were investigated. The temperature increase due to a hydriding exothermic reaction during the powderization of DU was bigger than that of ZrCo. However, as the hydriding amount increases, the temperature increase owing to the hydriding reaction of the two metals was very similar.