Experimental and computational investigation is carried out to elucidate the influence of stoichiometric mixture fraction on extinction of nonpremixed dimethyl-ether (DME) flames. Measurements are made employing the counterflow configuration. The counterflow burner used in the experimental study has two ducts. From one duct, called the fuel-duct, a fuel stream made up of DME and nitrogen is injected toward the mixing layer. From the other duct, called the oxidizer duct, an oxidizer stream made up of a mixture of oxygen and nitrogen is injected. The mass fraction of the reactants at the boundaries are so chosen that the adiabatic temperature is fixed. The values of the stoichiometric mixture fraction changes from 0.1 to 0.8. The strain rate at extinction is measured as a function of the stoichiometric mixture fracture. With increasing values of the stoichiometic mixture fraction the strain rate at extinction is found to decrease and then increase. Computations are performed with detailed chemistry. The predictions agree with measurements at small values of the stoichiometric mixture fraction, but significant differences are observed at high values of the stoichiometric mixture fraction. Sensitivity analysis was carried out to investigate the reasons for the differences between measurements and computations. © 2017 Eastern States Section of the Combustion Institute. All rights reserved.