[en] The kinetics of the reaction of ethylene oxide with O(³P) atoms has been investigated in detail using a discharge flow system with mass spectrometric and photometric detection. Absolute measurements of the rate constant, kinetic isotope effect, and stoichiometry have been made. The overall stoichiometry is 3 +- 1 oxygen atoms consumed per ethylene oxide molecule. Arrhenius parameters for the reaction of C₂H₄O with O are A = 10/sup (9.28+-0.08)/ L mol^-1 s^-1 and E = 5250 +- 150 cal mol^-1 over the temperature range 298 to 691⁰K, and Arrhenius parameters for the kinetic isotope effect are A/sub H//A/sub D/ = 0.9 +- 0.20 and E/sub D/--E/sub H/ = 1460 +- 230 cal mol^-1, over the temperature range 482 to 691⁰K. The magnitude of the preexponential factor and the temperature dependence of the isotope effect establish that hydrogen abstraction, rather than insertion to form a dioxetane intermediate, is the sole reactive channel for ethylene oxide plus O(³P). The Arrhenius parameters are discussed and compared to other hydrogen abstraction reactions of O(³P). Comparison is also made to the reactions of O(³P) with other strained three-membered ring compounds. The final products H₂, H₂O, HCHO, CO, and CO₂ were identified, and a mechanism is proposed to account for their formation from the radical products of the initial step