Fuel cells and hydrogen (FCH) systems are increasingly considered in energy and climate policies, roadmaps and plans all over the world. In order to avoid past criticalities, such as those leading to a climate emergency situation, sustainability criteria are being progressively implemented in these initiatives, e.g., by promoting low-carbon renewable hydrogen in Europe. In this regard, science-based criteria and procedures are required to guarantee the environmental suitability of FCH products, reporting their life-cycle environmental profile according to the principles of transparency, traceability, reproducibility, and consistency for comparability. While these principles are aligned with those of the general methodological guidance for Product Environmental Footprint (PEF) studies, further specification is required to effectively implement them when addressing FCH products. Hence, the HyPEF project aspires to support and promote the establishment of an environmentally-responsible hydrogen economy by developing and testing the first Product Environmental Footprint Category Rules (PEFCRs) specific to FCH products, while paving the way for subsequent related initiatives in the FCH sector. HyPEF is conceptualised as the natural step forward in methodological specification towards policy- and market-relevant life-cycle environmental assessment and benchmarking of FCH products. The interdisciplinary approach behind HyPEF leads to crucial advancements regarding (i) the first development and application of well-accepted PEFCRs tailored to three pre-selected FCH product categories (electrolysers for hydrogen production, tanks for hydrogen storage, and fuel cells for hydrogen stationary use), (ii) increased high-quality data availability for consistent environmental assessment and benchmarking of FCH products, and (iii) first PEF-oriented policy recommendations towards official qualification of an FCH product as an environmentally-responsible investment.