Based on Pt and heteropoly compounds (HPC), catalysts are applied to liquid-phase oxidation of cyclohexane and cyclohexene with a mixture of O-2 and H-2 gases. Platinum catalyst in the presence of PW11 and PW11Fe HPC represent the most active catalytic systems for alkene oxidation, whereas highest reactivity of cyclohexane was exhibited in the presence of PMo12 HPC. Activity of the catalytic systems and composition of the oxygenated products are controlled by the nature of active intermediates generated under the action of the different HPC. (C) 2003 Elsevier Science B.V. All rights reserved.