The applicability of sulphur aromatic parameters, based on ratios of dibenzothiophene (DBT) and its alkylatedhomologues, as indicators of oil maturity has been investigated in 27 oils from the Damintun and Zhuanhua Depres-sions, Bohai Bay Basin. The oils were characterised by bulk composition and environmentally-sensitive aliphatic bio-markers and were derived from a wide range of lacustrine source depositional environments ranging from highlyreducing hypersaline (sulphur-rich oils) to terrestrial input-dominated freshwater (very high wax oils) with maturitiesranging from immature to probable mid-mature. Dibenzothiophene-based maturity parameters are not well-correlatedwith sterane isomerization ratios, and immature oils, in particular, could not be discriminated by these aromaticmaturity indicators. In contrast, DBT-based parameters are strongly-correlated with pristane to phytane and Ts/Tmratios. High methyldibenzothiophene ratios (MDR) are associated with fresh water source deposition whilst lowMDRs are found in oils of hypersaline source affnity. Unusually high relative concentrations of 2+3-MDBT wereobserved in some of the immature oils inferred to be sourced by lacustrine organic laminites. The data provide furtherevidence that thermal stress is not the sole factor controlling the distribution patterns of dibenzothiophenes in oils andthat source depositional environments can exert a dominant in