The decompositions of monobromamine (NH2Br) and dibromamine (NHBr2) have been studied using an Applied Photophysics SX.18MV stopped-flow system at pH above and below 8.5 where each species is dominant. The reactions were monitored spectroscopically at 232 and 278 nm, the maximum absorbance wavelengths of NH2Br and NHBr2, respectively. The NH2Br decomposition reaction is 2nd order with respect to NH2Br concentration, results in the formation of NHBr2 and NH3, and is reversible. The forward and backward reactions are both acid catalyzed. NHBr2 decomposition was found to be responsible for the total bromamine decomposition at all pH values (6.6-9.3) investigated. A bromamine decomposition kinetic model is proposed. Includes 5 references, tables, figures.