The need for an accurate, rapid and affordable method for the determination of nitrite ions is due to its toxic effects on humans at elevated levels in wastewater and drinking water. The electrochemical determination is faster, cheaper and less labor intensive. It is based on the study of the electrochemical oxidation NO₂^- ion at different carbon electrodes. In this work, it was established by the cyclic voltammograms for the ISEM-3 graphite electrode has excellent limit of detection to nitrite ions: 5 × 10⁻⁶ М at pH 3, which makes it possible to determine the NO₂⁻ content below the maximum permissible concentration (6.5 × 10⁻⁵ M) in water.