The oxidation of the following ami no compounds with ozone in aqueous solution (pH 7–2) was investigated: “4–chloroaniline, 2–aminophenol, 4–aminobenzoic acid, 4–amino–2–nitrophenol, 4–amino–5–hydroxynaphthalene–2,7–disulfonic acid, 4–aminobenzene sulfonic acid ( initial conentrations 1 mmole1). Total destruction of the compounds is achieved with 4 to 6 mmole ozone mmole amine. 20–40 % of the amine nitrogen is found as ammonia and a small part as nitrate (4%). In the initial stages of the ozonation the solutions turn colored. In the further course of the reactions the colored intermediates are oxidized and after 6 mmole ozone/mmole amine the solution are colorless. In all cases the colored intermediates are not or only to a small extend biodegradable but the final oxidation products are better biodegradable.