Diatom rich sediments are often known for their hydrocarbon potential. A few notorious examples include the Miocene Monterey Formation in California, the Miocene Diatom Suite in Azerbaijan and the Menilites Formation in the Carpathians. In the Paratethys realm the diatomaceous sediments are widespread in the Oligo-Miocene strata, however their hydrocarbon potential still require attention. For this reason, five location were proposed for this study. The study sites include two Oligocene outcrops in the Western Black Sea Basin and three Miocene outcrops: one in the Eastern Carpathian Bend Zone, one in the Pannonian Basin and another one in the Alpine-Carpathian Foreland Basin. Apart from one outcrop from the Western Black Sea Basin, all the studied sediments were diatom-rich. However, the results indicate that the diatom rich sediments can vary significant in their hydrocarbon potential. For example, the sections studied from Ruslar Formation, Upper Menilites, and the diatom-free İhsaniye Formation proved to have a fair to very good hydrocarbon potential. The Source Potential Index calculations indicate that the above studied sections can generate on average 0.2 tHC/m2. The sections found to have poor hydrocarbon potential are represented by the Limberg Member and the non-calcareous part of the diatomites from Szurdokpüspöki quarry. The study sections give a small insight on the Paratethys connections. For example, the brackish water “Solenovian event” [NP 23] has not been observed in the studied sections on the Black Sea coasts. It seems to be hidden in the unexposed lower part of the Ruslar Formation and is probably missing at Karaburun. Moreover, Sibiciu de Sus diatomites indicate that the depositional sequence was deposited during or after the marine connection was closed between the Eastern and Central Paratethys, and before the deposition of the evaporitic sequence (NN3/NN4 zones). The Pannonian Basin System was covered entirely by the Miocene Paratethian Sea which is observed in the Limberg Member and the Szurdokpüspöki diatomites. Furthermore, in the studied sediments the diatoms frustules are found to be abundant and exceptionally well-preserved. Exception makes the Limberg Member, where the diatoms were highly broken most probably due to the high energy environment. After all, this thesis provides only a glimpse in the Paratethyan diatom world and advocate for further diatom biostratigraphy studies.