alpha-Substituted cycloalkanones are oxidized to oxo-acids by low-nuclearity complexes (Cu2+ or [VO2](+)/[VO](2+) - exchanged Nafion (R) beads), or homogeneous systems with ruthenium acetate complexes and [Ru(H2O)(6)] (tosylate)(2) in dioxygen (0.1 M Pa) at 55-60 degrees C.The catalytic procedures compare well with previously described systems involving homogeneous catalysis with copper (II) or polyoxometalates such as "H-8[PMo7V5O40].aq". The results complement the widely used oxidative methods for ketone cleavage in cases when protons and transition metal salts are involved. A tentative dioxygenase mechanism, involving peroxygen species, is proposed for these reactions. (C) 2010 Elsevier B.V. All rights reserved.