Five wells along a north-south trending section in the southern Eromanga Basin were studied using petrographic techniques to delineate petroleum source rocks and possibly aid in environmental interpretation. The dispersed organic matter (d.o.m.) in the Birkhead Formation is dominated by vitrinite and exinite, and examination of coal microlithotypes shows the precursors to have been large woody trees relatively free of alteration before burial. Exinite dominates the lower half of the Namur Sandstone Member, which consists predominantly of sands deposited in a braided fluvial environment, while the upper part of this unit contains equal proportions of all three maceral groups. Similarly in the Murta Member the d.o.m. in some wells is exinite-rich, but in others is evenly spread between maceral types. The Murta Member was possibly deposited in a freshwater lake which experienced periods of anoxic conditions. The Transition Beds show a comparable d.o.m. content to the Murta Member, although with less indication of terrestrial source material, coupled with evidence of periods of anoxia, and may have been deposited in a shallow marine environment. The Murta Member shows the most source rock potential of all the formations studied, and contains abundant Type-I kerogen. The overlying Transition Beds also contain Type-I kerogen but to a lesser extent. Additional source rock potential exists in the Birkhead Formation with Type-II kerogen being present in significant amounts. Vitrinite reflectance measurements place the maturity of these sediments in the pre-oil to early oil generation stage.