This reddish-yellow gas crystallizes as orange crystals at −59 °C. As one of several oxides of chlorine, it is a potent and useful oxidizing
agent used in water treatment and in bleaching.
Chlorine dioxide is used primarily (>95%) for bleaching of wood pulp, but is also used for the bleaching of flour and for the disinfection of municipal drinking water. The Niagara Falls, New York water treatment plant first used chlorine dioxide for drinking water treatment in 1944 for phenol destruction.