Platinum electrodes modified with a cellulose acetate membrane or with poly(1,8-diaminonaphthalene) film were assembled and used for rapid amperometric detection of nitrites and nitrates in water by batch and flow injection analysis.Parameters such as the permeability of the electropolymerised films to nitrites and nitrates, interference effects and recovery studies of these kinds of sensors have been optimised to demonstrate the analytical suitability of the proposed method.Contrary to the standard colorimetric method, which is based on carcinogenic reagents, the amperometric detection of nitrites and nitrates is very simple and rapid and does not require any reagent for nitrite detection. Also, this method could be extended easily to the analysis of nitrites and nitrates in various types of samples such as food, soils, vegetables and fertilisers.