A single detailed kinetic mechanism for the oxidation and combustion of n-decane and n-heptane has been written by means of an automatic mechanism generator ( REACTION) developed in our laboratory. It shows a good prediction of the ignition delay time versus temperature for the oxidation of n-decane at 13 and 50 bar and n-heptane at 13 and 40 bar for different equivalence ratios. The n-decane/n-heptane mechanism consists of a validated and recently published O-2=H-2=C-1-C-4 mechanism produced manually and a generated C-5-C-10 set of sub-mechanisms. The mechanism includes a complete description of both n-decane and n-heptane chemistry. This mechanism has a reasonable size, 506 species and 3684 reactions, but nevertheless it has an extensive range of chemistry. This paper represents not only the validation of a specific mechanism but also a validation of the rate constants of the reaction classes used to model the oxidation of alkanes at low and high temperature.