The oxidative properties of N2O3 and NO+ ion towards methyl or methylene groups of enolizable ketones are tested at 25 degreesC in homogeneous and heterogeneous acid systems. The results in concentrated aqueous sulphuric acid show that reasonable good yields (similar to95%) of benzoylformic acid from acetophenone are obtained at selected acidity ranges. A kinetic study for the conversion reagents-products and a thermodynamic treatment of the rates was also attempted by using the acidity dependence of rates, the equilibria of the reacting species and the departure from the ideality of the catalytic acid system. On the replacement of aqueous acid solutions with solid acids, benzoyl cyanide is instead obtained, with high yields and selectivity over catalysts with suitable acidic properties. Additional studies of different ketones and of certain alcohols are also reported. (C) 2004 Published by Elsevier B.V.