The development of hydrogen gas (H2g) as an energy vector will involve the optimization of many components (valves, pistons) subjected to tribological loadings (friction, wear). Hydrogen weakens metals and is also low lubricant. There is still little research in the field of tribology under H2g atmosphere. The objective of the TrHy project is to provide knowledge in this field by pooling the scientific and technical skills of the laboratory CMAT UMR 7633(EMP), specialist in the study of material damage and having a pressurized H2g platform, of the laboratory LTDS UMR 5513 (ECL) specialist in the field of tribochemistry and the laboratory LMPS UMR 9026 (CS) which develops a competence in the field of micromechanical characterization of surfaces. A first objective will be to adapt a tribological bench type plan/ plan to be enclosed in the CMAT pressurized H2g vessel. A fundamental research (co-supervided thesis CMAT, LTDS) will be set up to study the tribological response of two model steels 52100 (Martensitic) and Inox 316L (austenitic) under dry air, argon (inert) and more amply under pressurized H2g. Wear laws taking into account the contact loadings (pressure, slip amplitude, frequency), the microstructure of the steels studied and the effect of the gaseous environment will be established. An in-depth analysis of tribochemistry processes and microstructural transformations will be undertakens to establish damage scenarios. A dedicated post doc (LMPS, CMAT) will develop a research to characterize the micromechanical behavior of the rubbed layers weakened by hydrogen. Taking into account the available experimental data, multiphysical modeling taking into account hydrogen embrittlement will be implemented to predict the wear kinetics and more particularly the local wear of the interfaces studied.