Chlorine dioxide is a chemical compound with the formula ClO2 that exists as yellowish-green gas above 11 °C, a reddish-brown liquid between 11 °C and −59 °C, and as bright orange crystals below −59 °C. It is an oxidizing agent, able to transfer oxygen to a variety of substrates, while gaining one or more electrons via oxidation-reduction (redox). It does not hydrolyze when it enters water, and is usually handled as a dissolved gas in solution in water. Potential hazards with chlorine dioxide include health concerns, explosiveness and fire ignition. It is commonly used as a bleach.