Corrosion rates of iron in chromate and nitrite solutions were measured by a sensitive electric resistance method supplemented by weight loss. The critical concentration below which corrosion increases or pitting occurs is for and for . Presence of Cl− and increases these values. Sulfates break down passivity in nitrite solutions more so than do chlorides; the reverse is true of chromate solutions. Minimum concentration of passivator to avoid pitting in presence of Cl− or follows the relation where and are molarities of salt and passivator respectively. In chromate solutions in the alkaline range of pH, the corrosion rate is low (0.08 mdd) and no pitting occurs. In the acid range, corrosion remains low to at least pH 2.8 provided is used to adjust pH; when is used instead, the corrosion rate increases below pH 5 and pitting begins at pH 3. At temperatures up to 100°C, the steady‐state corrosion rates in chromates remain low (− or with the passivator ion for a site on the passive film. The data support the view that adsorbs more strongly than does .