This research explores competences that are essential for global leaders, i.e. expertise, skills, abilities and personalities. The aim is to discover a general set of competences that are very common in both literature and practice but exceedingly vital to be efficient global leaders. Another objective is to identify the most successful methods of development for the competences identified. The theoretical aspect of this research provides an outline of the literature on the topic and directions to an outstanding framework of competences relevant to global leaders from different researchers' perspectives. The most successful approaches for improving these competences are also identified. The experimental section, which is the standard study of the research, is based on a review of the literature. The research findings are compared with the findings of the literature review to create a set of competences for global leaders by semi-structured interviews with global business leaders. The key findings of this research indicate that personality traits are the most important attribute among global leaders and they are deep into the core of an individual. The most important competences for global leaders are therefore also those that are most difficult to change. Increased lifechanging development experience is required to affect such competences.