For over 30 years, European Union programme Erasmus+ plays a key role in internationalisation of European higher education institutions, which have developed their strategies, processes and activities to support and strengthen international cooperation and internationalisation in general through Erasmus+ activities. Despite being mostly connected to mobilities for students, Erasmus+ supports also higher education staff mobility to impact their professional and career development. What are the motives of academic staff to attend the mobility and how are these connected to impact of their experience is the main question of the thesis. Based on the motivation theories, national regulation of academic profession in higher education system and existing research about the impact of Erasmus+, I interpret the results of the analysis of questionnaires of Erasmus+ mobility participants from programme period 2014 – 2020. Which are supplemented by the findings from focus group with mobile teachers from Slovenian universities. We can differentiate motives based on the seniority of the academic staff. For junior staff motivation is connected to building up contacts, expending networks and reinforcing cooperation with partner institutions that usually leads to new projects, deeper research work in the field and new international scientific publications that can influence their career development. For senior staff motives are connected with reinforcement of the collaboration, to maintain and strengthen the network with the intention to further deepen the knowledge in the field, to improve the quality of teaching and research, to share knowledge with students and to reinforce the reputation of the institution.