[en] This publication presents and reports the different phases of the building up of an economic and industrial sector for renewable hydrogen production in the Centre Val de Loire Region. The first phase aimed at the identification of existing projects and of actors interested in hydrogen: description of the approach, classification of identified actors, major current projects, synthesis of interviews, identification of potential ecosystems in the concerned territory. The second phase comprised the organisation of training day which aimed at the acculturation of actors. The third phase aimed at the building up of ecosystems through the organisation of collective work-groups on two main themes (hydrogen ecosystems, industrial sectors) in order to identify expectations of actors regarding the region and projects. A second document contains a Power Point presentation of this approach