Fuel cells and electrolysers represent one of most promising alternatives for electrical energy production and storage. Today these technologies rely on nanoparticles (NPs) dispersions as electrocatalysts for the reactions of interest. A lot must be still done to acquire a full understanding of the phenomenon that occur at the surface of the NPs. Moreover, some concern is raising toward the possibility of the NPs to be dispersed in the environment during devices duty-life, promoting long-term health and environmental hazards. To overcome this issue, novel embedded catalysts should be developed, with a strong anchoring to a wide-area macroscopic substrate. Our proposal aims to characterize the evolution of a Ruthenium embedded electrocatalyst, used for Hydrogen Evolution Reaction (HER) in electrolysers, via operando XAS. Particularly, we intend to study the ruthenium/ titanium oxide substrate interaction which strongly influences the electrocatalyst performances