On the occasion of the International Year of Crystallography, and of the centennial of the award of Nobel prizes related with the discovery of X-ray diffraction, the Library of Physics and Chemistry (Biblioteca de Física i Química) of the University of Barcelona organized in 2014 an exhibition on the historical evolution and the bibliographic holdings of these two closely related subjects. This chronology, far from being comprehensive, provided the conceptual basis for the exhibition, collecting dates, authors and main achievements.