In this paper, we are going to present a methodology for gathering user requirements to design industrial collaborative robots. The study takes place within CoLLaboratE, a European project focusing on how industrial robots learn to cooperate with human workers for performing new manufacturing tasks, considering four use cases. The project follows a User-Centered Design approach by involving end-users in the development process. The user requirements will thus be gathered by applying a mixed methodology, with the purpose of formulating a list of requirements which can be generalized, but also case specific. This methodology is preliminary, and it will be improved during the following months, when the data will be collected and analyzed.