Two-dimensional current and potential distributions in a flow-by packed bed electrode have been measured with the test solution of CuSO4/Na2SO4. A mathematical model describing a rectangular flow-by packed bed electrode below limiting currents has been developed. Comparisons of current and potential distributions between the simulated and experimental results have been made, and fairly good agreements with each other have been reached. A mass transfer correlation has been obtained from limiting - current measurements, and it can be expressed as follows j(D) = 1.864 Re-p(-0.59) 10 < Re-p < 140 The performance of metal recovery by packed bed electrodes in circulating operation has been studied, and the concentration of cupric ion was reduced from 900 ppm to below 3 ppm. The experimental concentration-time curves are well predicted from the numerical results of the mathematical model.