Europe transition to a decarbonized energy system started in 2015, with the ratification of the Paris Agreement, and is set to transform the energy market, revolutionizing energy generation, distribution, storage and consumption. In this landscape, hydrogen from renewable sources will play an enabling role and related technologies, primarily electrolyzers and fuel cells, are set to take center stage in the energy market. To date, activity is aimed, on the research front, at untangling existing knots to maximize system performance, and on the industrial front, at actively promoting the development of production and supply chains capable of supporting a fast-growing market. The symposium aims to provide tools to appreciate the fundamental role of hydrogen as an energy carrier for decarbonization. The complexity of the challenge on the industrial front and the prospects for its use in different sectors will be described. The complexity of the industrial challenge goes hand in hand with a great deal of scientific interest that aspires to provide the tools needed especially for the optimization of catalysis systems.