Sodium Pyrosulfite or sodium metabisulphite is an inorganic compound of chemical formula Na2S2O5. The substance is sometimes referred to as disodium (metabisulfite, etc.). It is used as a disinfectant, antioxidant and preservative agent.

For food additive uses, It is used as a preservative and antioxidant in food. Sodium Pyrosulfite and potassium metabisulfite are the primary ingredients used for wine and beer making.

For sanitization and cleaning agent uses, Sodium Pyrosulfite is commonly used in homebrewing and winemaking to sanitize equipment. It is used as a cleaning agent for potable water reverse osmosis membranes in desalination systems. It is also used to remove chloramine from drinking water after treatment.

It is used in photography.

Concentrated Sodium Pyrosulfite can be used to remove tree stumps.

It is also used as an excipient in some tablets, such as paracetamol.