High Temperature Proton Exchange Membrane fuel cells, also known as High Temperature Polymer Electrolyte Membrane fuel cells, are a type of PEM fuel cells which can be operated at temperatures between 120 and 200°C.

High temperature hydrogen attack, also called hot hydrogen attack or methane reaction, is a problem which concerns steels operating at elevated temperatures (typically above ) in hydrogen-rich atmospheres, such as refineries, petrochemical and other chemical facilities and, possibly, high pressure steam boilers.