Hydrogen peroxide (H2O2) is the simplest peroxide. It is a chemical compound that is a combination of hydrogen and water. It is clear and has a slightly higher viscosity than water and often appears colorless in a dilute solution. The clear liquid acts as a mild antiseptic and comes at a variety of different potencies that have multiple uses. At 3% dilution, hydrogen peroxide is commonly used as a home cleaning agent. At 6-10%, it is used for bleaching hair. At 35% dilution, it is used as a food-grade cleaning agent. Hydrogen peroxide at 90% dilution is used almost exclusively for industrial purposes.

Hydrogen peroxide also has an oxidizing capacity that is so strong that is considered highly reactive. This means that hydrogen peroxide also has multiple utilities as a propellant in rocketry.