The catalysed oxidations of hydrocarbons were found to involve radicals and to be inhibited effectively by phenolic scavengers. The dependences of the activities of the catalysts on their concentrations are explained by the structural changes in the inverse micelles, from the first small spherical associates through an open-layered more active structure, which finally folds back by forming a hollow spherical closed structure, with a fall in the rate. The V-51 NMR spectral behaviour of the ion-pair catalysts and the colour changes in the solutions are discussed. The decavanadate structure is not destroyed entirely during the catalysed oxidation, in spite of the partial reduction of the V(V) centres and some structural deformations. The essential role of water and the influence of the products of oxidation by O-2 on the courses of the reactions are also discussed. (C) 2002 Elsevier Science B.V. All rights reserved.