Tantalum(IV) iodide is an inorganic compound with the chemical formula TaI4.

It dissolves in water to give a green solution, but the color fades when left in the air and produces a white precipitate.

This makes it difficult to produce a very pure crystallized tantalum(IV) iodide.

[4] Single-crystalline tantalum(IV) iodide was first obtained in 2008 by Rafal Wiglusz and Gerd Meyer as a chance product of a reaction in a tantalum ampoule that was supposed to lead to the product Rb(Pr6C2)I12.

The crystal structure differs from that of other transition metal tetraiodides, which usually have a MI4/2I2/1 chain structure, as it consists of TaI6 octahedra bridged over a common surface to form a dimer.