Investigation of the total oxidation of n-hexane and trimethylamine as well as extensive characterizations of the catalyst after tests have been coupled to identify the mechanism of oxidation involved over a very active gamma-MnO2 catalyst. This work shows that the extent of the catalyst reduction, which is a consequence of the Mars and van Krevelen redox mechanism, depends on the nature of the organic molecule. Indeed, the nature of the VOC dictates its conversion level through its ability to reduce the catalyst and accelerate the incorporation rate of gaseous oxygen. (C) 2006 Elsevier B.V. All rights reserved.