The oxidation of sulfur compounds in kerosene was conducted with tert-butyl hydroperoxide (t-BuOOH) in the presence of various catalysts. The oxidation activities of dibenzothiophene (DBT) in kerosene for a series of Mo catalysts supported on Al2O3 with various Mo contents were estimated. The results show that the oxidation activity of DBT increased with increasing Mo content up to about 16 wt.% and decreased when Mo content was beyond this value. The oxidation of benzothiophene (BT). dibenzothiophene (DBT), 4-methyl dibenzothiophene (4-MDBT), and 4,6-dimethyl dibenzothiophene (4,6-DMDBT) dissolved in decalin was also carried out on 16 wt.% Mo/Al2O3 catalyst with t-BuOOH to investigate the oxidation reactivities of these sulfur compounds. The results indicated that the oxidation reactivities of these sulfur compounds decreased in the order of DBT > 4-MDBT > 4,6-DMDBT much greater than BT. Analyses of the oxidative reactions of the sulfur compounds suggested that the oxidative reaction of each sulfur compound can be treated as a first-order reaction. The oxidation mechanism is then discussed. (C) 2003 Elsevier B.V. All rights reserved.