Dicalcium phosphate, also known as calcium monohydrogen phosphate, is a dibasic

Dibasic

Dibasic is an adjective meaning:# containing two hydrogen atoms that can be replaced by metal ions, or# "of or relating to salts or acids forming salts with two atoms of a univalent metal."...

 calcium phosphate

Calcium phosphate

Calcium phosphate is the name given to a family of minerals containing calcium ions together with orthophosphates , metaphosphates or pyrophosphates and occasionally hydrogen or hydroxide ions ....

. It is usually found as the dihydrate, with the chemical formula of CaHPO₄ • 2H₂O, but it can be thermally converted to the anhydrous form. It is practically insoluble in water, with a solubility

Solubility

Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent to form a homogeneous solution of the solute in the solvent. The solubility of a substance fundamentally depends on the used solvent as well as on...

 of 0.02 g per 100 mL at 25 °C. It contains about 29.5 percent calcium in its anhydrous form.
Dicalcium phosphate may be formed by the reaction of stoichiometric quantities of calcium oxide

Calcium oxide

Calcium oxide , commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline crystalline solid at room temperature....

 and phosphoric acid

Phosphoric acid

Phosphoric acid, also known as orthophosphoric acid or phosphoric acid, is a mineral acid having the chemical formula H3PO4. Orthophosphoric acid molecules can combine with themselves to form a variety of compounds which are also referred to as phosphoric acids, but in a more general way...

:

CaO + H₃PO₄ → CaHPO₄ + H₂O.

Dicalcium phosphate is mainly used as a dietary supplement

Dietary supplement

A dietary supplement, also known as food supplement or nutritional supplement, is a preparation intended to supplement the diet and provide nutrients, such as vitamins, minerals, fiber, fatty acids, or amino acids, that may be missing or may not be consumed in sufficient quantities in a person's diet...

 in prepared breakfast cereals, dog treats, enriched flour, and noodle products.