This presentation will detail the development of THera™ SEAL, a novel sealing technology specifically targeted towards high-pressure gaseous hydrogen storage applications. The innovative design of the metal-to-metal contact surfaces, integrated within the storage openings, remove the need of using a separate sealing element such a gasket or an O-ring. The presentation will delve into the design choices that contribute to its leak-tightness and pressure resistance within demanding hydrogen environments: dedicated thread and seal geometry design, computational analysis of local stresses and deformations, precise manufacturing tolerances, full-scale qualification testing. Used in combination with the high strength, quenched and tempered fully martensitic steels used in THera™ products, this sealing system also expands the allowable service temperature range, enhancing operational safety and efficiency.