Niobium(IV) iodide is an iodide of niobium, with the chemical formula of NbI<sub>4</sub>.
Niobium(IV) iodide can be obtained by the decomposition of niobium(V) iodide under a vacuum at 206-270 ðC.
Niobium(IV) iodide is a grey solid that reacts with water.
Niobium(IV) iodide is an orthorhombic crystal with space group Cmc2<sub>1</sub> (No. 36). Its crystal is formed by NbI<sub>6</sub> octahedra connected by edges and also contains Nb-Nb bonds. At 348 to 417 ðC, the crystal structure of niobium(IV) iodide changes. Niobium(IV) iodide turns into a metal under extremely high pressure.