The rate coefficient for the IO + ClO --> products (5) reaction was measured by coupling discharge flow and pulsed laser-induced fluorescence techniques. Rate coefficients were measured from 200 to 362 K by monitoring the temporal profile of IO in an excess of ClO The rate coefficient is described by the expression : k(5)(T) = (5.1 +/- 1.7) x 10-(12) exp[(280 +/- 80)/T] cm(3) molecule(-1) s(-1) where the quoted uncertainties include estimated systematic errors, Atomic iodine was identified as a major product of reaction 5. A branching ratio of Phi = 0.14 +/- 0.04 at 298 K was obtained for the sum of channels which do not produce I atoms.