In the framework of the undeferrable energy transition, all the possible evolutive trajectories of the Mediterranean energy system stem from the interaction of three triangles: a triangle of energy attributes (security, sustainability and equity) that should drive the configuration of the future energy systems; a geographical triangle, related to the three Mediterranean macro-zones (Northern, Eastern and Southern), with differences in terms of socio-economic and energy features; a commodity triangle, including electricity, hydrogen and gas, whose interplay will be central in implementing the decarbonisation. The investigation of the interrelationships among these triangles is crucial in understanding the multi-dimensional dynamics of the Mediterranean area – taking into account not only the sustainability perspective but also the social, economic, security and geopolitical issues – and to define strategic policies able to concretely achieve the energy transition and to improve the socio-economy development of the whole region. In this context, an important role could be played by green hydrogen, helpful for decarbonising the end-use sectors hard-to-abate and to support the decarbonisation of the other sectors. Hydrogen could represent an opportunity for the Mediterranean region, but it strictly requires a cooperative approach among countries. Focusing on the role of hydrogen, the 2021 edition of the MED & Italian Energy Report aims therefore at completing a triptych of studies: from natural gas (ENEMED 2019), which embodies the present energy dialogue based on fossil fuels, to electricity (ENEMED 2020), which represents the key commodity for a transition to a new renewables-based dialogue, to hydrogen (ENEMED 2021), which could support the decarbonisation of the final energy uses and, consequently, the achievement of the tight goals of climate neutrality.