Cenomanian Middle Sarvak rock samples were collected from various parts of the eastern Iranian sector of the Persian Gulf and analyzed for quantity, quality, maturity and depositional environment of the organic matter by Rock–Eval pyrolysis, gas chromatography (GC), gas chromatography–mass spectrometry (GC–MS), pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS), kerogen stable carbon isotopic signatures, elemental composition and petrography. The results indicate that the organic matter has mainly good to very good hydrocarbon generation potential corresponding to kerogen types I, II and II-S. The maturity increases from immature in the western section to early mature in the eastern section of the study area. In addition, biomarker parameters indicate a marine carbonate depositional environment for the Middle Sarvak Formation and deposition under anoxic condition. According to hydrocarbon potential, maturity and oil-source rock correlation, the Middle Sarvak is the main source rock charging the Late Cretaceous Upper Sarvak/Ilam reservoirs of south-eastern part of the Persian Gulf.