The electrochemical response of highly boron-doped conductive diamond electrodes to Ce3+ ions in aqueous sulfuric acid, nitric acid and perchloric acid solutions was studied mainly by use of cyclic voltammetry, The diamond electrode shows a well-defined voltammogram indicating quasi-reversible behavior for the Ce3+/Ce4+ redox couple in aqueous acidic solution. The equilibrium redox potential of the Ce3+/4+ couple was derived from the cyclic voltammograms. The diffusion coefficients for Ce3+ were evaluated from the dependence of the cyclic voltammograms on the potential sweep rate. The kinetic parameters for the anodic oxidation of Ce3+ were measured at the diamond electrode from the relation between the overpotential and the logarithm of current,