A mathematical model for the removal of impurities of the metal ions of Fe, Ni, and Cu from. hard chromium plating solution by electromigration and subsequent electrodeposition has been developed,and presented, Experimental data for the metal removal at 45degreesC and constant cell voltage using o-phosphoric acid as the. catholyte are presented. Up to 36% iron and 29% nickel removal is obtained over about 25 h. The copper removal rate is observed to be approximately four times greater than the rate of nickel removal. The experimental data were found to closely match results predicted from the model developed. The inherent model parameters such as mobility, diffusivity, mass transfer coefficient and metal deposition rate constants were estimated, The calculated values of these parameters are found,to be in good agreement with the published data.