The chemical structure of a premixed n-decane/O-2/N-2 flame (equivalence ratio 1.7) stabilized at atmospheric pressure on a flat-flame burner has been computed with two reaction mechanisms. In the first one, the consumption of the fuel molecule is described in detail. The five different n-decyl radicals formed by H atom abstraction from the decane molecule were distinguished and their consumption reactions were considered iq a systematic way. This mechanism comprises 78 species involved in 638 elementary reactions, Modeling with this detailed mechanism led to species mole fraction profiles in good agreement with the experimental results. The main reaction paths for the formation of final and intermediate species have been identified with special emphasis on benzene formation. The second mechanism was derived from the first one by successively removing an increasing number of n-decyl radicals. For most species, it is possible to maintain the reliability of the model with only one n-decyl radical in the mechanism. In this simplified version of the mechanism, the species number is reduced to 62 and the reaction number to 467. The only species affected are the large intermediate olefins.