?Copper II oxide; CuO; Molar mass 79.545 g/mol. Also known as cupric oxide, tenorite Copper(II) oxide??s an??norganic compound, a stable oxide of copper. It is used as a pigment to produce a ceramic glaze with a range of colours. It is a component of some wood preservatives. As a precursor, copper oxide is used in chemical reactions to produce many other copper-containing products and chemical compounds.