Abstract
Kinetic and static methods for creation of thermodynamically active hydrogen are discussed. High pressure devices for investigation of formation and decomposition equilibria of metallic systems in the presence of high pressure gaseous hydrogen are described. Furtheron a high pressure X‐ray device for similar purposes is presented. Details of formation and decomposition equilibria are discussed for the following systems: Ni‐H, Ni‐D, Cr‐H, Pd‐Rh‐H, Pd‐Pt‐H, Ni‐Fe‐H, and Pd‐Ag‐H.