The heterogeneous exchange of ferric ion between a labelled aqueous ferric chloride solution and some differently prepared ferric (hydr)oxides [(1) a freshly formed “amorphous” ferric (hydr)oxide, (2) ferric oxide obtained by drying the freshly formed precipitate in the air at 165 °C for 4.5 hours, (3) ferric oxide obtained by boiling the freshly formed precipitate in water at 100 °C for 4.5 hours] was investigated at room temperature. The exchange rate decreased in the sequence: (1), (2), (3), that sequence being attributed to the recrystallization of the solid phase in the sense of lattice ordering and particle growth, related to the treatment of freshly formed precipitate before the solid was put in contact with the ferric chloride and labelled. System (1) corresponded to a positively charged precipitate near the equivalency of the system FeCl3 + NaOH, and the exchange was governed by a rapid recrystallization (particle growth), initiated by labelling59FeCl3 solution in an acid (HCl) medium. In the system (2) selfdiffusion is indicated as the exchange governing process. The radionuclide54Mn, being present without isotopic carrier in labelling59FeCl3 solution and introduced into the liquid phase, remained in the liquid phase of systems (2) and (3).