Two men walk into a bar. One orders H2O. The other says „I'll have H2O too“. The second man dies. Hydrogen peroxide (H2O2) is the simplestperoxide (a compound with an oxygen-oxygen single bond). It is also a strongoxidizer. 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.