To tackle the climate crisis, humanity urgently needs renewable and decarbonized energy sources. A promising solution lies in harnessing dihydrogen (H2), and enzymes known as [FeFe] hydrogenases can play a vital role in its production. These enzymes catalyze the reversible oxidation of dihydrogen, employing an active site called the 'H-cluster,' a complex organometallic structure. The intricate biosynthesis of this cluster involves three maturation proteins: HydG, HydE, and HydF. Despite recent progress, a full understanding of this process remains elusive due to the complexity of the chemical reactions involved. Our goal is to conduct a structural study combined with step-by-step reaction monitoring using spectroscopy. This approach aims to identify and characterize various reaction intermediates of one key enzyme in the process. This collaborative project involves two leading CEA teams specializing in the study of oxygen-sensitive metalloproteins. The doctoral student will benefit from an ideal scientific and technical environment to achieve this objective, crucially important for advancing hydrogen economy development.