The structural properties of the solid phase, formed by the hydrolysis of Fe3+ ions in Fe2(SO4)3 solutions at 90 or 120-degrees-C, were investigated using X-ray diffraction, Fe-57 Mossbauer spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy. The concentration regions of Fe2(SO4)3 were determined for the precipitation of goethite, alpha-FeOOH, or hydronium jarosite, H3OFe3(OH)6(SO4)2, as a single phase. Superparamagnetic behaviour of alpha-FeOOH particles was observed. Hydrolysis of Fe3+ ions in 0.1 m Fe2(SO4)3 Solutions at 120-degrees-C produced H3OFe3(OH)6(SO4)2 and basic sulphate, Fe4(OH)10SO4. The interpretation of Fe-57 Mossbauer and FT IR spectra is given.