Hydrogen peroxide (H2O2) is the simplest peroxide (a compound with an oxygen-oxygen single bond). It is also a strong oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. Due to its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent. The oxidizing capacity of hydrogen peroxide is so strong that it is considered a highly reactive oxygen species. Hydrogen peroxide is therefore used as a propellant in rocketry. Organisms also naturally produce hydrogen peroxide as a by-product of oxidative metabolism. Consequently, nearly all living things (specifically, all obligate and facultative aerobes) possess enzymes known as catalase peroxidases, which harmlessly and catalytically decompose low concentrations of hydrogen peroxide to water and oxygen. H2O2 adopts a nonplanar structure of C2 symmetry. Although chiral, the molecule undergoes rapid racemization.
Contributions by Wolfkeeper, Physchim62, and Vsmith.