Cavity ring-down spectroscopy was used to study the title reaction in 50-200 Torr of O-2 diluent at 233-333 K. There was no discernible effect of total pressure, and a rate constant of k(BrO + C2H5O2) = (3.8 +/- 1.7) x 10(-12) cm(3) molecule(-1) s(-1) was determined at 293 K in 150 Torr total pressure Of 02 diluent. The addition of 1.4 x 10(17) molecules cm(-3) of H2O vapor had no measurable impact on k(BrO + C2H5O2) at 293 K and 150 Torr. The rate constant exhibited a negative temperature dependence and was described by k(BrO + C2H5O2) = 6.5 x 10(-13) exp((505 +/- 570)/T) cm(3) molecule(-1) s(-1). Results are discussed with respect to the atmospheric chemistry of BrO radicals.