In the Regional Museum in Nowe Miasto Lubawskie there is a bronze censer (thurible), which was found in a bog near the village of Jamielnik. Its body consists of two half-globes decorated with eight plaques showing lion's heads. The lid is topped with an octagonal tower, covered with a dome formed of eight leaves and crowned with a wide-armed cross (fig. 1-3). Mediaeval censers of this shape are very rare. Images of similar censers can be found on the cup of the chalice from St. Marien-Andreas church in Rathenow (central Germany) of the second quarter of the 13th c. (fig. 4) and on Prince Konrad of Mazovia paten from Plock, of the mid 13th c. (fig. 5). Also the motif of lion's head is an unusual ornament. The lions on the Jamielnik censer are reminiscent of Romanesque door-knockers. It remains to be investigated who, when and where made this artefact. The village where it was found used to belong to Chelmno County, which Prince Konrad of Mazovia leased to the Teutonic Order in 1226. Therefore, the vessel might have been commissioned by a Teutonic Order knight. Stylistic analogies to the art of Lower Saxony suggest that the censer was made by an artisan from Germany. He cast the vessel following the models that he knew in his homeland, but he probably made it in Poland. A technological analysis indicates that the censer was cast in a poorly equipped workshop and its form suggests that the workshop was far from large casting centres, which in the 13th c. mostly produced thuribles modelled after architectural forms. The Jamielnik censer is in the transition style: it shape and decoration clearly derive from the Romanesque tradition while the proportions and openwork design are Gothic. Comparative, stylistic and technological analyses allow us to date it to the second half of the 13th c. or the turn of the 14th c. at the latest. Hence, it may be the oldest preserved thurible that has been cast within the present territory of Poland.