The Nukhul Formation is the oldest syn-rift rock unit in the Gulf of Suez rift system in Egypt. The age of the formation is inadequately resolved by biostratigraphy and it is generally assigned to the Lower Miocene by stratigraphic position. For this study a surface section was measured and sampled at Wadi Baba, located in the southwestern Sinai Peninsula. It yielded 17 planktonic foraminiferal species and 17 foraminiferal benthonic species. The planktonic foraminiferal assemblage was used to divide the formation into two planktonic foraminiferal zones: (1) Globigerina ciperoensis Zone (O6) of Late Oligocene Chattian age; and (2) Globigerinoides primordius Zone (M1) of Early Miocene Aquitanian age. The two zones coincide with depositional sequences: (1) Chattian Lower Nukhul Sequence, with its upper boundary coinciding with the Chattian/Aquitanian (Oligocene/Miocene) boundary; and (2) Aquitanian Upper Nukhul Sequence, with its upper sequence boundary coinciding with the Aquitanian/Burdigalian boundary.