Hexadentate 8-quinolinolato manganese(III) complexes (Q(3)Mn(III)) developed by us, with the help of NH(4)OAC and HOAc, were found to efficiently catalyze the mild oxidation of thioanisole with aqueous hydrogen peroxide in environmentally benign acetone-water media. The ligand's halogen substituents Could improve the catalytic efficiency of Q(3)Mn(III) complexes,and this is likely that they can strengthen the distorted effect of Q(3)Mn(III), as supported by B3LYP/6-311G (d) calculation. The adjusting effect of additives on this sulfoxidation was also investigated and their mediation mechanisms were proposed. (C) 2009 Elsevier B.V. All rights reserved.