High-Entropy materials are characterized by multiple elements (≥5) that randomly occupy the same site in the lattice, forming a single crystalline structure and a homogenous compound, not a composite. These new compounds can be obtained under certain conditions, such as high temperature. The first discovered HE materials were High-Entropy Metal Alloys (in 2004), and more recently this was followed by oxides, carbides, nitrides and other compounds. We have recently started to investigate some of these materials for energy conversion applications.