During production of 1200 kg of cellulose nitrate, wrong manipulation on stirred tank reactor induced reaction and a release of 17 m³ of nitrogen oxides during one hour. Alarm system was activated, the personnel is evacuated and the plant shut-off. The public is alerted. No people were injured during the accident. Waste water is polluted with acid mixture but there is no evidence of significant ecological harm. The cost of damages has been estimated in about 7,500 DM. Despite operating instructions, the operator opened a wrong valve and the unreacted acid/cellulose mixture was released to a sewage whereby nitrogen oxides was released into the environment. After the accident, the warning and emergency plans have been revised.