# What Is The Use Of Oxidizer In Rocket Engines?

A rocket engine uses stored rocket propellants as reaction mass for forming a high-speed propulsive jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust in accordance with Newton’s third law.
Liquid oxygen or LOX is used as the oxidizer. The boosters use aluminium as fuel with ammonium perchlorate as the oxidizer, mixed with a binder that creates one homogenous solid propellant. The fuel for the main engines i.e. Hydrogen is the lightest element and normally exists as a gas.