A new mechanism for hydrogen embrittlementWhile hydrogen interaction with metals is well-documented at ambient temperatures, its behaviour under extreme heat, such as the temperatures inside power generation and aviation turbines, remains far less understood. At elevated temperatures, hydrogen atoms migrate to carbon vacancies within the alloy’s carbides, causing partial decomposition. Methane formation: Hydrogen and carbon atoms react to form localised methane gas. Redesigning superalloys: Because carbides are traditionally added to strengthen high-performance superalloys, metallurgists must now design alternative microstructures that balance high-temperature mechanical strength with hydrogen resistance. By identifying carbides as the primary catalyst for high-temperature hydrogen cracking, the study provides a mechanistic framework to help engineers design safer, hydrogen-resistant alloys for future green energy and aviation infrastructure.