Green hydrogen from renewable resources is one of the most critical levers for counteracting global warming caused by anthropogenic greenhouse gas emissions and, at the same time, increasing energy security. Green hydrogen is about to move from an early innovation stage to an industrial scale. Leaders can shape this transition using ecosystem theory. We used an exploratory mixed-methods study design to investigate the architecture of such an ecosystem with actors and the characteristics with objectives, roles, and key activities. We interviewed in the first step 22 experts using a semi-structured interview guide and facilitated in the second step a focus group discussion with 24 participants to test the insights gained from the expert interviews for their practicality. The data analyzed by qualitative content analysis revealed four main actor segments sufficient to describe participation in the green hydrogen ecosystem (GHE). The focus group discussion adds a fifth group, which could be described as the central expert council actor segment, which optimizes the processes between the actors, emphasizing that all actor segments are pursuing a common objective, the decarbonization under the Paris Agreement from 2015. Three actor segments in the ecosystem are identified as leaders to realize the common objective: equipment and service providers, governments and authorities, and the hydrogen market. The subjective perception of a low return on investment, considering the efforts an actor needs to contribute to the joint value creation and the achievement of the actor's individual objectives, is with the actor segments with the leadership responsibility. In the medium to long term, this could lead to tensions and an imbalance in the ecosystem, which could be mitigated by a more transparent distribution and allocation of key activities in proportion to the achievement of objectives.