An electrolytic cell and a method of electrochemical oxidation of manganese(II) ions to manganese(III) ions in the electrolytic cell are described. The electrolytic cell comprises (1) an electrolyte solution of manganese(II) ions in a solution of at least one acid; (2) a cathode immersed in the electrolyte solution; and (3) an anode immersed in the electrolyte solution and spaced apart from the cathode. Various anode materials are described including vitreous carbon, reticulated vitreous carbon, woven carbon fibers, lead and lead alloy. Once the electrolyte is oxidized to form a metastable complex of manganese(III) ions, a platable plastic may be contacted with the metastable complex to etch the platable plastic. In addition, a pretreatment step may also be performed on the platable plastic prior to contacting the platable plastic with the metastable complex to condition the plastic surface.