Holmium(III) sulfate is a holmium compound with the chemical formula Ho<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>. A hygroscopic orange-yellow octahydrate exists.
Holmium(III) sulfate can be prepared by dissolving holmium(III) oxide in sulfuric acid:
Adding triethylamine produces a 1-D amine templated holmium(III) sulfate material.
Holmium(III) sulfate reacts with hydrogen sulfide to form holmium(III) sulfide at elevated temperatures.
Holmium(III) sulfate is a catalyst for orthohydrogen-parahydrogen conversion at cryogenic temperatures.
A holmium-silver sulfate (AgHo(SO<sub>4</sub>)<sub>2</sub>) can be synthesized from holmium(III) sulfate and silver sulfate: