Sodium hydrosulfite (Sodium dithionite, Sodium hypodisulfite, Na2S2O4) is a white crystalline sodium salt. It decomposes in the presence of atmospheric oxygen to afford sodium hydrogen sulfate. It has been prepared by reducing sodium hydrogen sulfite in sulfurous acid solution with zinc. It is widely used for the decolorization prior to dyeing of cloths in the textile industry.
Sodium hydrosulfite may be employed as a reducing agent for the reduction of graphite oxide in a study.
Sodium hydrosulfite has been used as a fluorescent quenching agent in the encapsulation of polynucleotides via production of asymmetric nanoparticles. It has also be used in the form of buffer for the elution of probe labelled proteins involved in the indentification of cellular targets of covalent kinase inhibitors via mass spectrometry method (MS).