The Congo Basin (also called Cuvette Centrale) in the Democratic Republic of the Congo (DRC) is probably the last continental-scale sedimentary basin that is still poorly known in terms of petroleum system and related hydrocarbon resources. Two exploration surveys in the 1950s and the 1980s revealed no evidence for the presence of oil. Since then, several studies, mainly reprocessing and reinterpreting these old data, aiming at estimating the petroleum potential of the Congo Basin have been conducted to promote exploration and attract investors. Several possible potential source-rock levels, petroleum systems and possible plays were designated as targets for exploration. Some studies have proposed potential giant deposits, suggesting that the DRC could become an important oil producer in the future. Stimulated by this renewed interest in the Congo Basin and the need to verify these optimistic conclusions, we re-analyzed the geological archives and samples stored in the collections of the Royal Museum for Central Africa. Based on new geochemical analyses, the Neoproterozoic and Early-Middle Paleozoic black shales appear to be barren (average Total Organic Carbon -C_org. ≈ 0.1 %). In contrast, the Permian black shales are gas-prone (type III, higher plant derived, C_org. is between 0.3 and 2.4 %), but immature to early mature. The overlying Jurassic and Cretaceous source rocks are of excellent quality (type I, dominantly algae, C_org. up to 25 %), but are too immature. In addition, we have re-visited and re-sampled some oil seeps in the field (along the Lukenie River and Lake Inongo) and conclude these to be due to anthropic pollution. In conclusion, with the current state of knowledge, there is no clear indication of active petroleum systems in the Congo Basin. However, these conclusions are based on a rather limited and incomplete geological and geophysical dataset. New exploration projects are needed to identify areas where Mesozoic source rocks might have reached maturity.