Ammonium chloride is an inorganic compound with the formula NH4Cl and a white crystalline salt that is highly soluble in water. Solutions of ammonium chloride are mildly acidic. Sal ammoniac is a name of the natural, mineralogical form of ammonium chloride.

The main application of ammonium chloride is as a nitrogen source in fertilizers such as chloro ammonium phosphate. This product is also used as:

• A flavouring agent in some types of liquorice
• A flux in preparing metals to be tin coated, galvanized or soldered.
• An expectorant in cough medicine.
• A feed supplement for cattle and an ingredient in nutritive media for yeasts and many microorganisms.