Cu(NO₃)₂·3H₂O, commonly known as copper(II) nitrate trihydrate, is a blue crystalline compound. It consists of one copper ion, two nitrate ions, and three water molecules. This compound is often used in laboratories and various industrial applications, including as a catalyst and in the production of other copper compounds. When heated, Cu(NO₃)₂·3H₂O decomposes, releasing nitrogen oxides and water vapor. It is soluble in water, making it useful in aqueous solutions for chemical reactions. Safety precautions are necessary when handling this compound, as it can be harmful if ingested or inhaled.