Oxidation on iron is a process that results in the formation of RUST. RUST is an orange-brown flaky coating that forms on iron and steel when they are exposed to oxygen and moisture. RUST is a form of corrosion, which is an electrochemical reaction between iron and oxygen in the presence of water or moisture. Oxidation on iron is a common problem for many metal objects, and it can cause them to become weak and brittle over time.