Thorium diiodide is an iodide of thorium, with the chemical formula of ThI2.

It is an electride with the ionic formula Th4+(I−)2e−2.

It is air-sensitive.

[3] Thorium diiodide cn be prepared by heating thorium tetraiodide in stoichiometric amounts of thorium:[3][4] It can also be prepared by directly reacting thorium and iodine:[4] Thorium diiodide can also be prepared from the decomposition of thorium triiodide at temperatures above 550 °C:[4] Like the diiodides of cerium, praseodymium and gadolinium, it has a metallic gold lustre and high electrical conductivity.

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