One of the oldest and largest uses for iodine is in the disinfectant area. An almost universally known product is "tincture of iodine" for household disinfectant use.
Certain iodides have found use in the catalyst system for producing stereospecific polymers such as polybutadiene rubber. Also the dehydrogenation of butane and butylene to butadiene has been shown to be catalyzed by iodine that is also useful in polymer production.
Other applications of iodine are as food supplements, X-ray contrast media, radioactive tracers, photographic processing chemicals, constituent of cutting fluids use in heavy machinery. The element is also used in metallurgy with titanium, silicon, zirconium and hafnium.