Electrochemical kinetics of Ce(IV), Cr(III) and V(IV) and their diethylenetriaminepentaacetic acid (DTPA) complexes are studied by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) on Pt-electrode. Kinetic parameters such as potential, limiting current, transfer coefficient, diffusion coefficients, and rate constants were examined. The EIS results confirm the results from CV and are in good agreement with the obtained experimental data. The Cr–DTPA complex rate constant of 2.1×10−4 cms−1, diffusion coefficient of 1.9×10−6 cm2 s−1 and the V–DTPA complex rate constant of 2.2×10−4 cms−1 and diffusion coefficient of 4.9×10−4 cm2 s−1 were obtained and compared with the Ce(IV)–DTPA complex. The Ce(IV)–DTPA complex appear to better satisfy the requirement of a suitable electrolyte for RFB applications than Cr(III)–DTPA and V(IV)–DTPA complexes.