The electromigration behaviour of carrier-free241Am–Am(III) in inert electrolytes, =0.1 (C10
), T=298.1(1) K, was studied. On the basis of the overall ion mobilities of241Am–Am(III) on pH between pH 5.5 and 12.9, the stoichiometric hydrolysis constants p
=23.8(9), and pK1=6.9(2) were obtained. For K4 a limitation of pK414.4(3) was possible, because no formation of anionic hydrolysis products in solutions pH12.9 was registered. The individual ion mobility of the241Am–Am3+ decrease in the range pH 5.5–3 from +6.85(15) up to +5.50(15)·10–4 cm2·s–1·V–1. Dependences of this effect on overall ionic strength, inert electrolyte anion, and the temperature of the electrolytes were studied in acidic and neutral solutions.