The oxidation of n-heptane and mixtures n-heptane-MTBE (50:50) and n-heptane-ETBE (50:50) has been studied experimentally in a high-pressure jet-stirred reactor in a wide range of conditions covering the low and high temperature oxidation regimes (570-1150 K, 10 atm, phi=1, 0.1% of fuel). The mole fractions of reactants, intermediates and final products have been measured. The influence of the additives on the formation of several pollutants has been addressed. The present results clearly show an influencing effect of MTBE and ETBE on the kinetics of n-heptane oxidation by a reduction of the mixture reactivity in the low temperature regime (570-800K). The results are interpreted in terms of knocking and non-knocking tendencies related to fuel structure and low temperature oxidation mechanism.