The laser photolytic production of the IO radical from N2O/I-2/N-2 mixtures was used to measure the radical absorption spectrum from 340 to 450 nm. Two new absorption peaks at 403 and 411 nm were observed along with an underlying continuum starting at about 420 nm and extending to about 350 nm. An absorption cross section of (2.8 +/- 0.5) x 10(-17) cm(2), in good agreement with previous measurements, was determined for the (4-0) band head at 427.2 nm. From the rate of formation of IO and the rate of loss of I-2, rate constants for the reactions O + I-2 --> IO + I and O + IO --> O-2 + I of (1.4 +/- 0.4) x 10(-10) and (1.2 +/- 0.5) x 10(-10) cm(3) s(-1), respectively, were derived. Finally, from the rate of decay of IO, a rate constant for the reaction IO + IO --> products of (8.0 +/- 1.8) x 10(-11) cm(3) s(-1) was obtained. All of the uncertainties expressed are 2 standard deviations derived from the statistical analysis and do not include estimates for possible systematic errors.