Modern society is rapidly changing. Accordingly, science education suggests that students have scientific thinking, scientific inquiry, scientific problem solving, scientific communication, scientific participation, and lifelong learning skills as essential competencies to cope with this future society. One way to develop the core competencies is for students to participate in small group scientific inquiry activities, which are collaborative learning. Understandably, the mechanisms by which students develop skills and knowledge through collaborative learning are very vital for students to learn productively with their peers in school. Simply put, understanding how collaborative learning works successfully must be considered. The emergence of leadership can be seen as an important factor in effective collaborative learning. Therefore, it is necessary to understand emergent leadership and its effect on collaborative learning. Hence, this study aims to explore the emergent leadership and leadership moves in activities to solve problems jointly by participating in small group scientific inquiry activities, which are cooperative learning, in the context of open-ended scientific inquiry classes. As a result of the study, the leadership of the idea management and development type was found immensely in the class that determines the research topic, and the leadership of the planning and organizing type was found most evident in the class that conducts the experiment. Leadership moves appeared during scientific research activities, but no specific patterns were observed. Students interacted with each other and appeared as leaders depending on the situation to solve the problems they faced. Moreover, this decentralized cooperation and leadership moves can be considered to contribute to the successful completion of scientific inquiry activities.