Fe(IO3)3 powders have been produced by co-precipitation of iron nitrate and iodic acid in aqueous solution. X ray diffraction studies show that the crystal structure is satisfactorily described in space group P63; the cell parameters and the atomic positions have been ascertained by Rietveld refinements. The nanometric size of the Fe(IO3)3 particles has been estimated from the full width at half maximum of the diffraction peaks and confirmed by atomic force microscopy observations. Although we find colour changes and small weight losses below 400 °C, the structure is found stable up to this temperature where it decomposes to form nanosized hematite α-Fe2O3 powder. Finally, Fe(IO3)3 nanopowder pellets exhibit second harmonic generation of the fundamental wavelength of a Nd:YAG laser.