A modified one-dimensional model (Premix) in conjunction with Chemkin II and a detailed kinetic scheme combining the chemistries of hydrogen, dimethyl ether and iso-octane combustion were used to investigate the effect of hydrogen addition on the chemical composition of laminar premixed dimethyl ether/iso-octane/oxygen/argon flames. In the current modeling study, the key reaction mechanisms responsible for the observed variation in mole fractions of some major species, including radicals H, O and OH, species CO, CO2 and CH4 as well as oxygenated products CH2O and CH3CHO, were defined. The numerical modeling was focused on both chemical and dilution and thermal effects of hydrogen addition. It was found that chemical effect of hydrogen addition induced a boosting in the oxidation process whereas dilution effect led to its inhibition. The higher the hydrogen level the higher was the magnitude of the phenomenon. Besides, the chemical effect of hydrogen addition induced an enhancement in the OH, O, CO, CO2 and CH4 mole fractions, whereas the dilution and thermal effect led to a lowering in the amount of these species. This latter phenomenon was more important than the first effect yielding a net decrease in the concentrations of the four species. In addition, it was found that CH2O and CH3CHO levels showed a dramatic decrease in peak height with hydrogen doping and that the contribution of the thermal effect of hydrogen addition to this lowering was more important than that of its chemical effect. Thus it can be concluded that the synergism between chemical and dilution effects played a paramount role in the dimethyl ether/iso-octane/oxygen/argon premixed flames oxidation process as well as in the rise or the decrease in the pool radicals and the major species concentrations. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.