The advancing digitalisation of science is changing the traditional role of employees at academic libraries. The scope is increasingly expanding to include topics relating to open science and the reproducibility of research processes and its results. Dealing with the ever increasing amounts of data requires more technical expertise and creates an entirely new range of tasks in the institutions. The required knowledge is still largely lacking as subject matter in library study programmes and can only be acquired sporadically in depth and in context. The ‘Data Librarian’ certificate course offered at TH Köln addresses this gap and is designed to teach basic data skills over a period of nine months in a combination of guided self-study phases and in-person sessions. In this article, a participant reports on whether and how this can be achieved.