磷酸一氢钠、磷酸氢二钠、磷酸氢钠，化学式为Na₂HPO₄，是磷酸生成的钠盐酸式盐之一。它为易潮解的白色粉末，可溶于水，水溶液呈弱碱性。磷酸一氢钠用作软水剂及食品工业中的添加剂。

它有很多水合物：

它可由氢氧化钠和磷酸以固定计量比中和生成：

它在240℃以上失水，分解为焦磷酸钠。

Disodium phosphate (DSP), or sodium hydrogen phosphate, is the inorganic compound with the formula Na₂HPO₄. It is one of several sodium phosphates. The salt is known in anhydrous form as well as forms with 2, 7, 8, and 12 hydrates. All are water-soluble white powders; the anhydrous salt being hygroscopic.