Holmium(III) selenate is an inorganic compound with the chemical formula Ho2(SeO4)3. It exists in the anhydrous form and as an octahydrate. It can be obtained by dissolving holmium(III) oxide in selenic acid solution and evaporating and crystallizing it.[1] It co-crystallizes with other selenates in solution to obtain complex salts such as K3Ho(SeO4)3·nH2O,[2] NH4Ho(SeO4)2·3H2O[3] and CH3NH3Ho(SeO4)2·5H2O.[4]