Two series of 0.001 M Fe(NO₃)₃ solutions, having NaOH/Fe molar ratios ranging from 0 to 3.1, were prepared by diluting a 0.5 mol/L Fe(NO₃)₃ stock solution with water and then hydrolyzed at 70℃. The preparation differed only in the initial temperature of the water for dilution; but the final products were very different in particle size, morphology and crysrallinity. In Series I solutions, prepared with 70℃ water the reaction products were amorphous, structureless masses initially, but became well crystallized goethite and/or hematite in the shape of rods or plates shortly afaer being aged at 70℃. In Series Ⅱ solutions, prepared with room temperature water, the hydrolyzed products were tiny spheres havin a well-defined outline and homogeneous size throughout the experimentation. They were very poorly crystallized goethite and/or hematite even after, 248 d of aging at 70℃ and could be detected only with a high power Rigaku rotating anode x-ray diffractometer. The results suggested that the temperature of water for solution preparation plays a key role in the size and nature of the initial hydrolytic product which, in turn, plays a key role in the rate of redissolution and recrystallization.