Bromoxynil was rapidly degraded in all aerobic soils with a half-life between one and seven days. Two derivatives bromoxynil heptanoate and butyrate had a half-life around one day and were metabolised to bromoxynil. Bromoxynil was further degraded to two major metabolites 3,5-dibromo-4-hydroxybenzamide and 3,5-dibromo-4-hydroxybenzoic acid. They immediately peaked around 10-20% AR after four days. The two metabolites themselves were quickly metabolised with a half-life shorter than a day to the major metabolites benzoic acid and 3-bromo-4-hydroxybenzonitrile which then further metabolised to carbon dioxide. 3,5-dibromo-4-hydroxybenzamide, 3-bromo-4-hydroxybenzoic acid and 4-hydroxybenzonitrile were detected as minor metabolites. The mineralisation is moderate to high and it was concluded that bromoxynil is unlikely to persist in the environment.