The kinetics and products of reaction I between gas-phase BrO and IO radicals have been studied using the technique of laser photolysis with time-resolved UV-vis absorption spectroscopy. The O + IBr reaction 8, used as one source of and BrO radicals, was found to produce predominantly IO radicals at 295 K. The rate coefficient for reaction 8 is correlated with the branching ratio for IO production (channel 8a). Using a value of 0.7 for the branching ratio for IO production (k(8a)/k(8)), k(8) was found to be (3.6 +/- 2.4) x 10(-11) cm(3) molecule(-1) s(-1) at 295 K, with no significant temperature dependence between 210 and 333 K. Sensitivity tests using a kinetic model showed that, in addition to (1), decay traces were also sensitive to the rate coefficient for reaction 12: 1 + BrO --> Br + IO. This rate coefficient was found to be (1.3 +/- 1.2) x 10(-11) molecule(-1) cm(3) s(-1) at 295 K, with no significant temperature dependence between 235 and 333 K. The title reaction (1), IO + BrO --> products was found to have a rate coefficient (8.5 +/- 1.4) x 10(-11)cm(3) molecule(-1) s-1 at 295 K. Reaction I exhibited a negative temperature dependence between 210 and 333 K, adequately described by ki = (6.7 +/-0.8) x 10(-12) exp ((760 +/- 30)/T) molecules(-1) cm(3) s(-1). No pressure dependence to k(1) was found between 100 and 760 Torr. All errors are 2 sigma. Five potential products exist for the IO + BrO reaction: IO + BrO --> I + Br + O-2 (1a), IO + BrO --> IBr + O-2 (1b), IO + BrO --> OIO + Br (1c), IO + BrO --> OBrO + I (1d), and 10 + BrO --> IBrO2 (1e). No direct measurement of I or Br formation was performed. IBr was observed as a minor product (k(1b)/k(1) < 0.2). OIO formation was observed and shown to result from the 10 + BrO reaction for the first time in this work. No evidence for OBrO formation was observed (k(1d)/k(1) < 0.15). No evidence for the formation or existence of IBrO2 was observed. The results obtained here, in conjunction with other published work, were used to constrain the branching ratio, alpha, for OIO production in the IO + IO reaction, giving {0.30 +/- 0.05 less than or equal to alpha less than or equal to 0.46 +/- 0.08}. This constraint allowed the absorption cross section of OIO to be constrained giving (1.29 +/- 0.22) greater than or equal to sigma (OIO) X 10(17) greater than or equal to 0.87 +/- 0.15) molecules(-1) cm(2) at the (5, 1, 0) peak at 549 nm, 295 K, and 760 Torr. Results are compared with previous studies of the 10 + BrO reaction, and the atmospheric implications are briefly discussed.