Tungsten(III) iodide or tungsten triiodide is a chemical compound of tungsten and iodine with the formula WI3.

Tungsten(III) iodide can be prepared by reducing tungsten hexacarbonyl with iodine.

[1][3] Tungsten(III) iodide is a black solid that releases iodine at room temperature, and is less stable than molybdenum(III) iodide.

It is soluble in acetone and nitrobenzene, and slightly soluble in chloroform.

[1] It decomposes to form tungsten(II) iodide:[1]