A process is provided in which the resulting Fe-tCDTA contrast agent has a reduced osmolality. The process according to the invention comprises the following steps:

a) preparing an aqueous solution of tCDTA and FeO(OH), tCDTA and FeO(OH) being present in a molar ratio of from 1:1 to 1:1.4;
b) b.1) adjusting a pH of the aqueous solution to between pH 2.5 and pH 4.5 by adding a base, preferably meglumine, and separating the precipitate; or

b.2) precipitating the Fe-tCDTA contrast agent from the aqueous solution by adding acetone, separating the precipitate, and preparing an aqueous solution from the precipitate; and


c) adjusting a pH of the aqueous solution to between pH 6.5 and pH 8.0 by adding a base, preferably meglumine, and separating the precipitated FeO(OH).