The motion of ions in an electric field for solutions containing Cu2+ ions in the presence of 2-phosphonobutane- 1,2,4-tricarboxylic acid (PBTC), N-trismethylenephosphonic acid (NTMP) and N-(phosphonomethyl) imino-diacetic acid (PMIDA) was investigated using a capillary electrophoresis analyzer. Satisfactory agreement between the cation isotachophoretic determination results and the results calculated from the protonation constants of the relevant ligand species and the stability constants of copper complexes was obtained. The research results can be useful for the electrokinetic method of removing copper from soil.