|The Eocene-Oligocene boundary in the Paratethys region represents a period associated with a major extinction event followed by Oligocene to Early Miocene anoxic events. Furthermore the Oligocene Menilite Formation or its stratigraphic equivalents sourced a number of petroleum provinces within the Paratethys area. The Menilite Formation in the territory of the Czech Republic is subdivided from base to top into the Subchert Member (NP22), Chert Member (upper NP22 to lower NP23), Dynów Marlstone (NP23) and Šitbořice Member (upper NP24 to lower NP25). To cover the whole sequence of the formation, a 40 outcrop samples from the Loučka section (Silesian Unit) was accompanied by 37 cores samples representing the Šitbořice Member of Ždánice Unit. The lithological variations represented by non-calcareous shales, marlstones and cherts reflect strongly varying depositional environment causing variations in both the geochemical parameters and hydrocarbon potential. The Loučka section where most of the Subchert Member, whole Chert Member and Dynów Marlstone and lowermost part of the Šitbořice Member are exposed represents an excellent opportunity to study the factors controlling the organic matter-rich layers deposition. The Menilite Formation contains mainly type II kerogen based on both the Rock-Eval hydrogen index (HI) and organic petrography. Type I kerogen was observed in the Chert Member (HI up to 725 mg HC/g TOC), while admixtures of type III kerogen were indicated predominantly in the Šitbořice Member. Based on the HItrue and organic petrography observations, type II and I kerogen prevails. The Menilite Formation holds mostly “good” source rock potential even the TOC ranges up to 16.5 wt%. The Chert Member is the most prolific among the members in both TOC (average 5.9 wt%) and petroleum potential (average 45.1 mg HC/g rock). The thermal immaturity of the organic matter was confirmed by Rock-Eval Tmax (from 400 up to 433°C) and vitrinite reflectance (from 0.24% to 0.31%). Considering the results of this study the Menilite Formation may represent very promising source rock even in the Czech Republic where other source rocks are in the foreground of interest. Higher thermal maturity which may reaches favourable conditions for hydrocarbons generation is expected especially beneath the Magura Group of Nappes.