This article attempts to describe the life and activities of Adam Trebnic, Archdeacon of Pomerania and Abbot of Oliva. It brings together for the first time all the possible historical sources on the figure of this abbot, who lived in Clairvaux at the beginning of the Reformation and introduced strict observance and abstinence to the Polish monasteries. In these monasteries, he also implemented the Citeaux monastic programme and maintained Catholicism.