The kinetics of the oxidation of L - methionine by bromate ions in aqueous acidic medium at a constant ionic strength, μ , of 0.50 mol dm–3 were investigated spectrophotometrically at temperature of 30.0 ± 1ºC. The reaction shows a stoichiometry of 1:2 (Methionine/ bromate), first order kinetics in [methionine], first order in [bromate] and second order dependence in [H+]. An increase in ionic strength and a decrease in dielectric constant of the reaction medium increase the rate of reaction. The reaction is catalysed by anions. Polymerization test conducted suggests the absence of free radicals. The results obtained from this study supports the operation of outer – sphere mechanism. A plausible mechanism is proposed for the reaction.