Samarium(III) iodide is an inorganic compound, a salt of samarium and hydroiodic acid with the chemical formula .
Samarium(III) iodide is prepared by the reaction of metallic samarium and iodine:
Samarium(III) iodide is a yellow powder that is unstable in air and decomposes in water (hydrolysis). When heated with metallic samarium, it forms samarium diiodide:
Reduction by hydrogen also affords samarium diiodide upon heating:
The compound is commercially available and used in organic reactions as a catalyst.