Mechanistic study of oxidation of cyclohexene was carried out over a copper complex and its immobilized analogue supported on organically modified silica. The immobilized complex has been characterized by using atomic absorption spectrophotometry (AAS), Fr-IR, EPR and UV-vis spectroscopic studies and SEM image analysis. Catalytic oxidation of cyclohexene was carried out over this copper complex and the immobilized analogue with different oxidants like dilute aqueous hydrogen peroxide and tert-butyl hydroperoxide at ambient conditions. Acetonitrile and water was used as solvent and dispersion medium, respectively, with or without additional acid in different sets of oxidation reactions. The mechanism of hydride shift initiated the study of benzene oxidation, which gave quinone as major product. The activity of the immobilized catalyst remains nearly the same after four cycles, suggesting the true heterogeneous nature of the catalyst. (c) 2006 Elsevier B.V. All rights reserved.