偏亚硫酸氢钠，化学式Na₂S₂O₅，是一种无机化合物。它当用作消毒剂、抗氧化剂及防腐剂。

白色或微黄色结晶，溶于水，水溶液呈酸性。此外亦溶于甘油，微溶于乙醇。在空气中易被氧化为硫酸钠。受潮易分解，且熔点为150°C。与强酸发生化学反应，并生成二氧化硫及相应盐类。

Sodium metabisulfite or sodium pyrosulfite (IUPAC spelling; Br. E. sodium metabisulphite or sodium pyrosulphite) is an inorganic compound of chemical formula Na₂S₂O₅. The substance is sometimes referred to as disodium (metabisulfite). It is used as a disinfectant, antioxidant and preservative agent.