Cupric Oxide (copper (II) oxide CuO) is a black crystal. It is used in making fibers, ceramics, gas analyses and for Welding fluxes. Cupric Oxide is used as a catalyst and in catalyst preparation. Cupric Oxide (CuO) is the higher oxide of copper. Cupric oxide is used as a pigment in ceramics to produce blue, and green glazes. Cupric oxide is used as flux in copper and bronze metallurgy, in galvanic electrodes, as solvents for chromic iron ores,and also used in manufacturing wood preservatives.