This study demonstrates that Cu(II) can significantly enhance the decomposition rate of bromamines. Apparent second order rate constants of 2.31 ± 0.01 M-1s-1 and 0.36 ± 0.01 M-1s-1 at pH 7.5 were determined for the reaction of Cu(II) with bromamines and the self-decomposition of bromamines, respectively. Increasing the pH from 6.0 to 8.5, the rate of bromamines self-decomposition decreased while the rate of Cu(II)-catalysed decomposition of bromamines increased. Species-specific rate constants indicated that Cu(OH)2 was the most reactive copper species towards NH2Br and NHBr2. Experiments were carried out with 15N-labelled bromamines to analyse the nitrogenous degradation products of bromamines in the presence and absence of Cu(II). Nitrogen gas (N2) was found to be the major product from the self-decomposition of bromamines, with N2O, NO2-, and NO3- as additional minor products. When Cu(II) was present, the product distribution changed and NO2- and N2O became significant, while N2 and NO3- were produced at low levels. Increasing the Cu(II) concentration from 1.0 to 5.0 mg/L increased the N2O production while decreased the NO2- formation. Based on these results, a mechanism for Cu(II)-catalysed decomposition of bromamines is proposed. This work provides new insights related to the chemistry of bromamines in chloraminated drinking water distribution systems where copper is present.