Final edited full-text version of the paper available at: http://www.sciencedirect.com/science/journal/02731177The Observatori de l'Ebre became operative in late 1904. From the beginning it was devoted to studying the influence of solar activity on Earth's physical phenomena. Ionospheric studies should be, as they are, an important part of its research activity. This article reviews the development of ionospheric research at the observatory and the main contributions the Observatori has made to ionospheric science.This research has been partly funded by Spanish DGI project HUM2004-04259/HIST.Peer reviewed