Sodium phosphite is a chemical compound with the formula Na3PO3. It appears as a white, crystalline solid and is commonly used in various industrial applications, including as a reducing agent and in the production of phosphite fertilizers. Sodium phosphite is soluble in water, making it useful in aqueous solutions. In addition to its industrial uses, sodium phosphite plays a role in the food industry as a food preservative. It helps to prevent spoilage and maintain the quality of certain products. Its properties also make it valuable in the synthesis of other chemical compounds, contributing to its versatility in different fields.