Most applications of iridium use its high melting point, high hardness and corrosion resistance properties. Iridium metal, as well as iridium-platinum alloys and osmium-iridium alloys, have very low losses and can be used to make porous spinnerets. Spinnerets are used to extrude plastic polymers into fibers, such as rayon. Osmium-iridium alloys can also be used in compass bearings and weighing scales.

Iridium is also often used in instruments that have to withstand high temperatures. For example, the Tchaikolaski process uses high-temperature crucibles made of iridium to produce individual oxide crystals such as sapphire, gadolinium gallium garnet, and yttrium aluminum garnet. These crystals are used in computer memory and solid-state laser parts. Iridium alloys resist arc erosion, making them ideal for spark plug electrical contacts.
The radioisotope iridium-192 is an important energy source in gamma radiography, which facilitates non-destructive testing of metals. In addition, brachytherapy uses gamma rays released by 192Ir to treat cancer. This treatment, which places a radiation source near or inside cancerous tissue, can be used to treat prostate, bile duct, and cervical cancer, among others.