Cost effective bulk storage in vessels and transport pipelines of hydrogen are key requirements to develop the hydrogen economy for the renewable sectors. However, hydrogen embrittles low cost, high strength materials, such as advanced steels. This project will address this major challenge by fundamentally linking a specific aspect of the microstructure, namely the nature of the grain boundaries, to the strength and propensity for hydrogen embrittlement. This will be achieved through composition and processing to produce different types of grain boundaries and then study their resistance to hydrogen uptake. This will lead to the design of microstructures that offer unique properties for applications such as hydrogen storage