Making science enjoyable inspires students to learn more. Out-of-class activities such as science fairs and Olympiads, serve as reasonable informal learning environments that demand attention. The association of students’ involvement in these activities with increased student interest in science followed by the selection of science-related careers, should motivate all in-charge stakeholders. In this work, we analysed the outcomes of the Bosnia Science Olympiad (BSO) as the first national Science Olympiad in Bosnia and Herzegovina (BiH), aiming the improvement of science education and bringing different ethnic groups under the umbrella of science, in a post-conflict area. The two-day endeavour held in Sarajevo includes competition in four science-related categories (Environment, Engineering, Have an Idea, Web Design) and social activities. In this work, the comprehensive data, including participants’ gender, their ethnic background, cities, schools, and supervisors, over five years, was analysed. The number of participating high-school students increased from 78 to 143, of supervisors from 21 to 95, and of schools from 7 to 15, reaching a wide demographic acceptance to cover all ethnic regions in BiH. The relationship between gender and the selection of a category, shows bias of male participants towards Web Design (21%) and Engineering (40%), and of female students towards “Have an Idea” (40%) and Environment (44%) categories. The contribution of BSO choosing a science career, getting socialized without prejudices, and the improvement of students’ self-confidence, were as well addressed. Our work demonstrates a model work to successfully promote science in post-conflict settings.