The author discusses a marble pluteus discovered in 1906 in the Kotor cathedral, where it was incorporated in the main altar as a spolium. Apparently, it originally belonged to the chancel screen in the sanctuary of St Tryphon, constructed in the early 9th century, of which only remnants of the foundation layer have been preserved. The pluteus has been analysed on several occasions, with the results published in scholarly literature, and most experts have justly dated it to the early period of pre-Romanesque sculpture in Dalmatia. Its front features a relief with geometric and vegetal ornaments. To the left, there is a panel with knotted triangles along the edge and rhombuses in the central section. The panel to the right contains two arcades with crosses underneath. Special attention has been paid to the relatively numerous ornaments on similar plutei in areas of Adrio-Byzantine tradition, in Roman cities of the Istrian and Dalmatian coastlines. Thereit combines with influences from Lombard and Carolingian centres, and in this combination it is also present in the area of the ancient Croatian state and other Sclavinias. The pluteus of Kotor is a telling element in the discussion on numerous similar relief arrangements and ornaments in the sacral art of the Adriatic cultural circle during the early medieval period.