A method for sensitive detection of nitrite is presented. It is found that the red fluorescence of gold nanoclusters (with excitation/emission maxima at 365/635nm) is quenched by traces of iodine via etching. Free iodide is formed by oxidation of iodide by bromate anion under the catalytic effect of nitrite. This catalytic process provides a sensitive means for nitrite detection. Under the optimal conditions, fluorescence linearly dropos in the 10nM to 0.8μM nitrite concentration range. The limit of detection is 1.1nM. This is a few orders of magnitude lower than the maximum concentration allowed by authorities. Graphical abstract Schematic representation of a method for detection of nitrite via a redox reaction. Iodine was produced in the reaction and subsequently quenched the fluorescence from gold nanoclusters by etching their metallic cores, and a sensitive assay fornitrite down to 1.1nM was developed.