Abstract: Catalytic oxidation of carbazole (CAZ) was investigated using oil-soluble t-butyl hydroperoxide (TBHP) as oxidant and Mo(VI) complexes as catalyst. The influences of various factors on CAZ conversion were probed including ligand, supporter and other metals Ni and Co involving. The results show that without supporter molybdenum acetylacetonate (Mo(VI)) has higher activity than MoO₃ because of its solubility in hydrocarbon. All supporters, Al₂O₃, weakly acidic cation exchange resin (D113) and weakly acidic chelating cation exchange resin (D751), can promote the activity of MoO₃. Incorporation of Ni and Co metals can reduce the activity of MoO₃/Al₂O₃. It is also found that in the presence of dibenzothiophene (DBT), TBHP/MoO₃/D113 presents a higher oxidation selectivity of CAZ, while TBHP/MoO₃/D751 has a similar oxidation activity to CAZ and DBT. The structure of CAZ oxidation product was speculated according to the spectrum data.