The Triassic rocks of the (West) Timor Basin have been identified that was mainly deposited in the marine environment. The fine grained
clastics and carbonate rocks of this Triassic marine facies are considered to be the most promising source rocks potential in this basin. In
this paper we present geochemical and petrographic data from outcrop samples of the Triassic carbonate Aitutu Formation, due to
emphasized the organic maturation, kerogen type of the organic matter and the origin of the organic matter. A representative of selected
sample were subjected to the Rock-Eval Pyrolisis, vitrinite reflectance and thermal alteration index, bitumen extraction, were analyzed on
the GC-MS. The samples were collected from marine deposit of the Triassic Sequence. The TOC values of the analyzed sample range
between rich and rich organic richness (0.51% – 9.16%, wt.%, TOC), which consists mainly of type II and III kerogen and the organic
matter consider to be predominantly oil/gas prone and gas prone potential. The thermal maturity assessed from Tmax, TAI, and vitrinite
reflectance shows an immature to early peak mature stage of the organic matter. The GC-MS analyses of the biomarkers indicate mainly
the organic matter derived from mixed source rocks facies containing alga debris and higher plant terrestrial origin.
Keyword: Source Rock Potential, Triassic, (West) Timor Basin.