次磷酸钠，化学式NaH₂PO₂。

次磷酸钠是一种无色单斜结晶或有珍珠光泽的晶体或白色结晶性粉末，易潮解，无臭，味咸。易溶于水、乙醇、甘油，稍溶于氨和氨水，不溶于乙醚。水溶液呈中性。在干燥状态下较为稳定，加热至200°C以上则迅速分解放出剧毒且自燃的磷化氢气体。为强还原剂，可将金、银、汞、镍、铬、钴等金属从盐中还原为金属状态。遇强热或与氯酸钾等氧化剂混合时会爆炸。常压下，加热蒸发次磷酸钠溶液也会发生爆炸，故蒸发应在减压下进行。

在美国，次磷酸钠与次磷酸和其他数种次磷酸盐被列为第一类易制毒化学品，受到管制。

Sodium hypophosphite (NaPO₂H₂, also known as sodium phosphinate) is the sodium salt of hypophosphorous acid and is often encountered as the monohydrate, NaPO₂H₂·H₂O. It is a solid at room temperature, appearing as odorless white crystals. It is soluble in water, and easily absorbs moisture from the air.