The rate of the reaction of nitrite with hypobromite/hypobromous acid was studied over a wide range of HI concentrations (6.5 less than or equal to - log [H+] less than or equal to 10). The kinetics were measured as a function of NO2-, H+ and total Br(I) ([HOBr](total) = [HOBr] + [BrO-] + [BrNO2]) concentrations. A mechanism is proposed for nitrite oxidation involving the reversible formation of BrNO2, which is then attacked by NO2- to yield N2O4 in the rate-determining step. The second-order rate coefficient k(1) for the latter reaction was determined at different ionic strengths in two aqueous media: NaCl and Na2SO4. Finally, a quantitative comparison of nitrite oxidation by HOBr/BrO- and HOCl/ClO- is presented.