A study of gel formation in iron(III) nitrate nonahydrate (Fe(NO 3)3 · 9H2O)-ethanol (C2H 5OH)-1,2-epoxypropane (propylene oxide (CH3CHCH 2O)) ternary system has been performed. The phase boundaries for existing ferrihydrite gels were determined. It was shown that this ternary system has two different types of ferrihydrite gel phases. The dominant chemical bonds of these phases were investigated by Fourier transform infrared spectroscopy (FTIR). Both ferrihydrite phases transform to amorphous α-FeOOH phase after 6 h annealing at T = 300 °C. The temperatures of crystallization from these amorphous α-FeOOH phases to α-Fe 2O3 phases were found.