三氯化磷，分子式：PCl₃。一种无色透明液体，沸点76℃，在潮湿空气中能水解成亚磷酸和氯化氢，发生白烟而变质，须密封贮藏。

PCl₃ + 3H₂O → H₃PO₃ + 3 HCl

遇乙醇和水起水解反应，

遇氧能生成三氯氧磷。

2PCl₃ + O₂ → 2 POCl₃

在水存在下，可与甲醇反应生成亚磷酸二甲酯。

反应分两步进行：
1.PCl₃ + 3H₂O → H₃PO₃ + 3HCl
2.H₃PO₃ + 2CH₃OH → HOP(OCH₃)₂ + 2H₂O

总反应为

PCl₃ + 2CH₃OH + H₂O → HOP(OCH₃)₂ + 3HCl

Phosphorus trichloride is a chemical compound of phosphorus and chlorine, having the chemical formula PCl₃. It has a trigonal pyramidal shape. It is the most important of the three phosphorus chlorides. It is an important industrial chemical, being used for the manufacture of organophosphorus compounds for a wide variety of applications. It has a P NMR signal at around +220 ppm with reference to a phosphoric acid standard.