Sodium hydroxide, chemical formula for NaOH, commonly known as caustic soda, caustic soda, caustic soda, is a highly corrosive alkali, usually flaky or granular form, soluble in water (soluble in water, heat) and the formation of Alkaline solution, otherwise deliquescent, easy to absorb water vapor in the air (deliquescence) and carbon dioxide (metamorphism).

Sodium hydroxide in water treatment can be used as a basic cleaning agent, soluble in ethanol and glycerol; insoluble in propanol, ether. Sodium carbon also has a corrosive effect at high temperatures. And chlorine, bromine, iodine and other halogen disproportionation reaction. Neutralizes acids and generates salts and water.