Sodium Formaldehyde Sulfoxylate also called Rongalite is a chemical compound with the molecular formula Na+HOCH2SO2−. This salt has many additional names, including Rongalit, sodium hydroxymethylsulfinate, sodium formaldehyde sulfoxylate, and Bruggolite. It is listed in the European Cosmetics Directive as sodium oxymethylene sulfoxylate (INCI). It is water-soluble and generally sold as the dihydrate. The compound and its derivatives are widely used in the dye industry. The structure of this salt has been confirmed by X-ray crystallography.