The kinetics of the reaction between ethoxy (C2H5O) radicals and O2 have been studied using a combined laser photolysis/LIF techniques for the generation and detection of C2H5O. At 295-411 K, the rate coeff. has been found to be k1 = (7.1 +- 0.7) * 10-14 exp[(-552 +- 64) K/T] cm3/s. Product investigations using a chem. titrn. of HO2 by NO and subsequent quant. detection of OH by LIF indicate the dominance of the HO2 formation channel, viz C2H5O + O2 -> CH3CHO + HO2..