Hydrogen is expected to play a key role as an energy carrier in the path towards global sustainability. Nevertheless, right decisions are needed to make fuel cells and hydrogen (FCH) systems effective in this crusade. Besides technological advancements, methodological solutions that allow checking the suitability of FCH systems under sustainability aspects from a life-cycle perspective are needed to sensibly support decision-making. Such methodological contributions should rely on well-defined guidelines that allow a reliable assessment and benchmarking of FCH systems. In this sense, sound guidelines for Life Cycle Sustainability Assessment (LCSA) of FCH systems are urgently needed. The goal of SH2E is to provide a harmonised (i.e., methodologically consistent) multi-dimensional framework for the LCSA and prospective benchmarking of FCH systems. To that end, SH2E will develop and demonstrate specific guidelines for the environmental (LCA), economic (LCC) and social (SLCA) life cycle assessment and benchmarking of FCH systems, while addressing their consistent integration into robust FCH-LCSA guidelines. These guidelines aim to be globally accepted as the reference document for LCSA of FCH systems and set the basis for future standardisation, going beyond the update of past initiatives such as the FC-HyGuide project and the IEA Hydrogen Task 36 through their reformulation to deal with underdeveloped topics such as material criticality and prospective assessment. For the sake of practicality and extended use of the guidelines, key SH2E outcomes also include user-friendly, open-access software tools with illustrative case studies, also being a source of publicly available data reviewed by a third party. Thus, the project is aligned with international initiatives towards global sustainability, including the Innovation Challenge on Renewable and Clean Hydrogen, by providing robust frameworks and tools that help decision-makers check the sustainability of FCH solutions.