Mercury oxide is toxic. Mercury oxide is an alkaline oxide, which is an inorganic substance, bright red or orange-red scale-like crystals or crystalline powder, practically insoluble in water, insoluble in ethanol, decomposes at 500°C, is highly toxic and irritating. Mercury oxide can be used to produce other mercury compounds, also used as catalysts, pigments, antimicrobial agents and mercury batteries in the electrode material. Mercury oxide can also be used as a catalyst for organic reactions, as an analytical reagent for the determination of zinc and hydrocyanic acid, for the detection of acetic acid in formic acid and carbon monoxide in mixed gases, for the preparation of organic mercury, and as a preservative. If you inhale mercuric oxide, quickly remove yourself from the scene to fresh air, keep warm, keep your airway open, and seek medical attention.