Herein are described the results of t-BuOOH aided air oxidations of (-)-alpha -pinene, catalysed by [Co(pyridine)(2)Br-2] or [Co(4-methylpyridine)(2)Br-2], and observations about the nature of the reactions. The use of a small amount of t-BuOOH showed a clear beneficial influence on air oxidation under mild temperatures. Raising the temperature did not increase yields markedly. An increase of the hydroperoxide concentration sped up air oxidation and brought up the amount of oxidised products, especially allylic ones. The oxygen atom in oxidised products was not derived from peroxide. Instead, the reaction needed the presence of molecular oxygen to proceed. The present air oxidation is a homogeneous catalytic reaction, and the formation of verbenone took place via trans-verbenol.