Protactinium(V) iodide is an inorganic compound, with the chemical formula of PaI<sub>5</sub>.
It can be prepared by the reaction of metals protactinium and iodine, or by reacting protactinium(V) chloride, protactinium(V) bromide or protactinium(V) oxide with silicon tetraiodide.
It reacts with antimony trioxide in a vacuum at 150 ðC to give the iodide oxides PaOI<sub>3</sub> and PaO<sub>2</sub>I; it reacts with protactinium(V) bromide at 350 ðC to obtain mixed halides PaBr<sub>3</sub>I<sub>2</sub>. It reacts with the monocarbide at 600 ðC to give protactinium tetraiodide.
Aristid von Grosse was able to produce pure metallic protactinium with the decomposition of protactinium(V) iodide.
When heated at 300 ðC for a long time, it decomposes and iodine is released: