Chemistry, reactivity, and mechanism of transition metal catalysed oxidation of benzylic compounds by means of ozone were systematically investigated. A significant influence of substituents on the reactivity of the benzylic position correlating with the Hammett coefficients of these substituents as well as with their steric influences was observed. It was shown, that mono-oxidation of compounds with different benzylic groups is possible in high regioselectivity and that the reaction seems to proceed via a mechanism including radical species. (c) 2005 Elsevier B.V. All rights reserved.