[en] The chemical behavior of iodine, I₂, in (pH = 6 to 10) aqueous solutions containing 2500 ppM boron as H₃BO₃ (0.231 M) was studied at temperatures up to 150⁰C. Absorption spectrophotometry was used to identify and monitor the iodine species present. The I₂ hydrolysis chemistry was found to be consistent with the two-stage mechanism: I₂ + H₂O reversible HOI + H⁺ + I^-, 3 HOI reversible IO₃^- + 2I^- + 3H⁺, where the intermediate species is designated as HOI to emphasize that its exact structure and composition are not defined. Three objectives were considered: (1) species identification, with special attention given to HOI; (2) the kinetics of reaction between iodine and water to produce iodide and iodate ions; and (3) partition coefficients between liquid and vapor phases for individual iodine species. Kinetic rate constants for the disproportionation of the HOI intermediate were measured. A typical activation energy for this reaction was found to be 28.4 kJ/mol (6.8 kcal/mol). Although some initial results had suggested an ionic strength dependency, a more detailed examination of the ionic strength effect on this disproportionation reaction suggests that the intermediate in solution throughout the pH 7 to 10 range is primarily an uncharged species such as the triatomic HOI. No absorption bands can be assigned to the HOI intermediate even though it has been shown, in some cases, to be present at concentrations of greater than or equal to 1 x 10^-3 M. A very low molar absorptivity (< 10 M^-1 cm^-1) is probably responsible for its undetectability. A partition coefficient of > 1 x 10⁴ has been estimated for HOI