Anode foil, preferably aluminum anode foil, is etched using a process of treating the foil in an electrolyte bath composition comprising a persulfate, a halide, an oxidizing agent, and a sulfate. An etch resist can be added to the anode foil prior to etching. The anode foil and the attached etch resist can be heated prior to immersing both in an electrolyte bath composition. The anode foil is etched in the electrolyte bath composition by passing a charge through the bath, while maintaining a constant level of persulfate. The etched anode foil is suitable for use in an electrolytic capacitor.