Online social networks evolved into a global mainstream medium that generates an increasing social and economic impact. However, many online social networks face the question how to leverage on their fast growing popularity to achieve sustainable revenues. In that context, particularly more effective advertising strategies and sophisticated customer loyalty programs to foster users’ retention are needed. Thereby, key users in terms of users’ connectivity and communication activity play a decisive role. However, quantitative approaches for the identification of key users in online social networks merging concepts and findings from research on users’ connectivity and communication activity are missing. Based on the design science research paradigm, we therefore propose a novel PageRank based approach bringing together both research streams. To demonstrate its practical applicability, we use a publicly available dataset of Facebook.com. Finally, we evaluate our novel PageRank based approach in comparison to existing approaches, which could alternatively be used.