The paper "Co-creation in the Early Stage of Product-service System Development" has been published within the new issue of Procedia CIRP (63, 2017). The paper was authored by the chair's researchers Aida Boukhris, Dr. Dr. Albrecht Fritzsche and Prof. Kathrin Möslein, and was presented at the 50th CIRP conference on manufacturing systems in Taiwan.This research examines the theme of co-creation with users, by integrating them at the early stage of development of product-service systems (PSS) for concept generation, or as it can be also called, at the fuzzy front-end. The authors start by evaluating the published methods for PSS development at the fuzzy front-end, then they derive a co-creation oriented method that relies on prototyping at selected stages of the process. The first stage deals with the generation of a shared understanding of the concept to be developed, and in the second stage we converge towards the generation of the user requirements by employing a set of electronic tools to drive process and logic flow thinking within the group of co-creators. The methodology has been evaluated within three workshops where participants were asked to design a decentralized bike-sharing system, where bike owners can generate revenues from their bikes by renting them out when not otherwise needed.