The high concentrations of multiple elements leads to slow diffusion. The activation energy for diffusion was found to be higher for several elements in CrMnFeCoNi than in pure metals and stainless steels, leading to lower diffusion coefficients. Some equiatomic multicomponent alloys have also been reported to show good resistance to damage by energetic radiation. High-entropy alloys are investigated for hydrogen storage applications. Some high-entropy alloys such as TiZrCrMnFeNi show fast and reversible hydrogen storage at room temperature with good storage capacity for commercial applications. The high-entropy materials have high potential for a wider range of energy applications, particularly in the form of high-entropy ceramics.