© 2022 Elsevier LtdThe Molla-Bismil area is a petroleum province, which hosts predominantly Paleozoic oil fields in the foreland area of the Diyarbakır Basin. The Arpatepe, Bahar, Yeniev, and Çalıktepe fields are Paleozoic oil field discoveries in the Molla-Bismil area to-date and have consequently been the focus of considerable research. This significant breakthrough reveals that the deep-wells in the Molla-Bismil area have proven the existence of a Paleozoic petroleum system. Prospective source rocks are located stratigraphically above the upper part of the Bedinan Formation (Upper Ordovician) reservoir, near the base of the Dadaş Formation (Llandovery, Dadaş-1 member). The lithology of the lower part of the Dadaş-1 member, also known as hot shales in the Molla-Bismil area, are typified by organic-rich brownish-black colored shale containing bitumen and thin limestone beds. New well data assists with the regional definition and correlation of typical source rock properties within the Diyarbakır Basin. Subsurface stratigraphy was derived for several deep wells from the Molla-Bismil area and core or drill cuttings from the Çatak-1, Bahar-1, Göksu-1R and Çalıktepe-2 wells were studied and reviewed for lithological and geochemical information. The understanding and prediction of the geochemical characterization of the Lower Silurian (Llandovery) organic-rich shales relevant for hydrocarbon production are crucial for Turkey's fossil fuel supply. Based on new drilling data, we re-examined the properties of the Llandovery organic-rich shales in the Molla-Bismil region. This study brings together new and previously unpublished knowledge about the Paleozoic plays of SE Turkey.