Hydrogen Peroxide is a substance having the chemical formula H2O2. It is a very light blue liquid when it is pure, somewhat more viscous than water. For consumer use, it is often used as a diluted solution (3%6% by weight) in water, while larger concentrations are employed in industry as an oxidant, bleaching agent, and antiseptic. High-test peroxide, also known as concentrated hydrogen peroxide, decomposes explosively when heated and has been employed as a rocket propellant.