[2] The high-temperature polymorph α-palladium(II) iodide can be produced by reaction of the elements at temperature above 600 °C.

The γ-modification is produced as an almost amorphous powder by addition of iodide salts to aqueous H2PdCl4 solution .

When heated in dilute hydrogen iodide solution, this polymorph transforms into the β phase at around 140 °C.

It reacts with iodide giving PdI42− anion: It finds use as a catalyst.

[5] Palladium(II) iodide is an almost X-ray amorphous black powder.