A discharge flow reactor with mass spectrometric detection has been used to determine the fractional yield of ethoxy, Y(EtO), from the reaction of F(P-2) with C2D5OH. The chemical titration method that was used depends only upon the occurrence of the fast chain reaction, F-2 + C2D4OH --> C2D4OH + F, and the ability to measure relative concentrations of ethoxy radical. Ethoxy concentration was proportional to the detected ion count signal at m/z 50. [Ethoxy] was titrated to an asymptote with a large excess of F-2. The titration removes hydroxyethyl radicals and regenerates F so that, at the asymptote, each F initially present will have formed one ethoxy radical. The experimental value of Y(EtO) is the ratio of the m/z 50 signal in the absence of F-2 to the signal in the presence of F-2. The measured values of Y(EtO) +/- (1 sigma) are 0.62 +/- 0.08 at 223 K, 0.55 +/- 0.06 at 300 K, and 0.39 +/- 0.02 at 423 K. An Arrhenius analysis of these data implies that the average activation energy for abstraction at a C-D bond is about 1 kcal/mol larger than that for abstraction at the O-H bond. The activation energy for attack at O-H is likely to be near zero. Allowing F(P-2) to react with large excesses of ethanol and F-2 provides a good clean source of ethoxy radical.