The purpose of this study is to explore critical aspects in the establishment of an open innovation arena. This study considers the perspective of science parks as the establisher and facilitator of the open innovation arenas. By understanding these critical aspects science parks and its participants can benefit from improved innovativeness. The results of this study indicate that there are a number of critical aspects important during the establishment of open innovation arenas by science parks. Among these critical aspects are the selection of participants, a neutral and passive stance on formalization of contracts and IP, the creation of trust and motivation within the arena, the importance of the physical arena setting and the benefit of an arena topic area prominent amongst the surrounding participants. In addition, this study shows the importance of science parks' neutral position, as well as the influence of the participants throughout all aspects. Based on these findings, practical and theoretical implications are presented and discussed in the paper.