The kinetics of the coordination of Fe(III) and 2,3-dihydroxy-benzenesulfonate (Tiron) has been studied under the condition of ionic strength 1.00 mol•L^－1, [H^＋] from 0.01 to 0.70 mol•L^－1 and [Fe(III)]>>[Tiron]. The reaction rate investigation showed that if [H^＋]≤3.00×10^－2 mol•L^－1, [Fe(III)]² has an unusual contribution to the reaction rate. Kinetic parameters for related reactions have been obtained. For an explanation of each rate constant and kinetic results, a dissociation reaction mechanism of complexation of [Fe(III)]², and Tiron, and an association reaction mechanism of , have been disclosed. A possible mechanism for the coordination reaction has been proposed.

Key words: iron(III), 2,3-dihydroxy-benzenesulfonate, complex, kinetics