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.

1. Food Industry: Preservative, bleaching agent and antioxidant (e.g. for candied fruits, preserved fruits, wine).
2. Printing and Dyeing Industry: Dechlorinating agent for bleached cotton cloth, auxiliary for vat dyeing.
3. Water Treatment: Deoxidizer for industrial circulating water, dechlorination agent for wastewater.
4. Chemical Industry: Reducing agent, electroplating additive, mineral processing agent.
5. Pharmaceutical Industry: Pharmaceutical intermediate, raw material for disinfectants.