More than 0.22 mmol of isolated VO4 species of V2O5/Al2O3 exhibited the highest evolution of the partial oxidation products (alcohol and ketone) in the oxidation of cyclohexane and cyclopentane. The conversion of cyclohexane and the selectivity of the partial oxidation products were achieved to be 0.49% and 85% over 0.8 g of 3.5 wt.% V2O5/Al2O3, respectively, where the K/A ratio was 6.2. In addition, V2O5/Al2O3 can selectively oxidize various hydrocarbons in the liquid phase by the one-step oxygen atom insertion to C-H bond. The order of priority was tertiary carbon > secondary carbon > primary carbon > benzene ring. (C) 2004 Elsevier B.V All rights reserved.