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