The products of corrosion reaction of electrolytic iron in 45% ammonium nitrate solution formed under various conditions of time, temperature and pH have been analyzed mainly by Mössbauer spectroscopy, in combination with x-ray diffraction, infrared absorption, and electron nticroscopy techniques. gamma-FeOOH is found to be the major product of hydrolytic precipitation at pH greater than 5.6 while only a alpha-FeOOH is formed at pH less than 3.0. In the pH range between 3.0 and 5.0, alpha-FeOOH and ferrihydrite are both formed. However, once the nuclei of alpha-FeOOH are formed under low pH conditions, their growth is favored even in the othenvise unfavorable slightly acidic medium, resulting in a hydrous alpha-FeOOH which has two distinct hyperfine fields as the ⁵⁷Fe nucleus. Magnetite is always formed in the vicinity of the metal and its rate of formation on the surface increases with temperature. alpha-Fe₂O₃, is the major product of hydrolytic precipitation at temperatures above 80°C. The possible mechanisms for the formation of each of the corrosion products are discussed. -- AATA