Sodium metabisulfite appears as a white crystalline or powder solid with a slight sulfur odor. Toxic by inhalation . Strongly irritates skin and tissue. Noncombustible, but may decompose to emit toxic oxide fumes of sulfur and sodium when heated to high temperature. A corrosive acid when mixed with water. Used as a food preservative and as a laboratory reagent. Sodium disulfite is an inorganic sodium salt composed of sodium and disulfite ions in a 2:1 ratio. It has a role as a food antioxidant. It contains a disulfite.

Used in the production of sodium hydrosulfite, sulfadimidine, metamizole sodium, caprolactam, etc.; for the purification of chloroform, sulfoxone and benzaldehyde.Used as a component of fixers in the photographic industry; for the production of vanillin in the fragrance industry; as a preservative in the brewing industry; as a rubber coagulant and dechlorinating agent for cotton fabrics after bleaching; as an organic intermediate.Used in printing, dyeing and leather tanning; as a reducing agent; for wastewater treatment in electroplating and oilfield industries, and as a mineral processing agent in mines.Used as a preservative, bleaching agent and leavening agent in food processing.