Promethium iodate is an inorganic compound with the chemical formula Pm(IO3)3. It can be obtained by reacting with potassium iodate, ammonium iodate or a slight excess of iodic acid and Pm3+ solution and precipitating it.[2] Its hydrate, Pm(IO3)3·H2O, crystallizes in the P21space group, with unit cell parameters a=10.172±13, b=6.700±20, c=7.289±24 Å, β=113.1±0.2°.[1]