Mercury(II) oxide is used in marine and porcelain paints, dry batteries, chemical reagents, and topical antiseptics. It acts as a significant part in the production of mercury. It is utilitarian in the deduction of a mercury based superconductor. It is likewise employed, as a photo-oxidant for the photochemical oxidation of primary aromatic amines to the corresponding azoaromatic compounds. It is also an essential material for the preparation of cathodes in mercury batteries.