Alumina-supported vanadyl complexes with ligands of ethylenediamine (en); [VO(en)(2)]SO4-Al(2)O(3)2-alum; tetramethylethylenediamine (TMED); [VO(TMED)(2)]SO4-Al(2)O(3)3-alum; bipyridine (bpy); [VO(bpy)(2)]SO4-Al(2)O(3)4-alum; 1,10-phenantroline (phen); [VO(phen)(2)]SO(4)Al(2)O(3)5-alum; acetylacetonato (acac); [VO(acac)(2)]-Al2O3; 6-alum; NAP-ethylenebis(salicylideneiminato) (salen); [VO(salen)]-Al(2)O(3)7-alum; N,N'-phenytenebis(salicylideneiminato) (salophen); [VO(salophen)]-Al(2)O(3)8-alum; catalyzed the oxidation of cyclohexene with tertbutylhydroperoxide(TBHP). The major products of the reaction were 2-cyclohexene-1-one. The influence of solvent and time for the oxidation reaction has been studied. The selectivity of the 2-cyclohexene-1-(tert-butylperoxy) varied with reaction time. Alumina-supported vanadyl catalysts with the nitrogen donor ligands show significantly higher catalytic activity than oxygen donor ligands at the same surface coverage. [VO(bpy)(2)](SO4)-Al2O3 shows significantly higher catalytic activity than other alumina supported vanandyl complexes. These catalysts can also be reused in the oxidation of cyclohexene for several times. (C) 2004 Elsevier B.V. All rights reserved.