Abstract A long history of petroleum production from the South Caspian Basin demonstrates this region's significant hydrocarbon resources. The world's first oil wells were located here in the early 19th century, and mechanized drilling led to increasingly advanced extraction programs from the mid-1800s into the Soviet era. Offshore areas, first explored in the 1930s, remain the object of significant interest and potential. Hydrocarbon reservoirs belong to the Productive Series (Miocene-Pliocene), a fluviolacustrine complex of sediment delivered by the paleo-Volga river system. Extremely high subsidence rates and closure of the lake basin contributed to a distinctive stratigraphy with basinwide layer continuity. A combination of oil-prone to mixed gas/oil basinal marine source rocks of Oligocene to Miocene sourced the petroleum. Hydrocarbon generation started in the basin about 4 Ma, with most generation and expulsion occurring in the last 2 m.y., the same time structures began to form in the basin. High fluid pressure gradients appear to inhibit the development of effective traps with seals, particularly offshore Azerbaijan where the occurrence of shale exceeds sand.