An electrode element for an electrolytic capacitor comprises an electrode body having a plurality of ultra-fine, ribbon-shaped filaments of Al and X (where X is selected from Nb and Ta) interspersed and aligned along an axis of the body. The Al filaments are preferentially removed from a portion of the electrode body to provide a large surface area electrode surface comprising exposed end surfaces of the Al filaments and exposed lengths of the X filaments protruding beyond the exposed end surfaces of the Al filaments. Dielectric oxide films are formed on the exposed surfaces of the Al filaments and on the exposed lengths of the X filaments by an anodizing operation. A solid or liquid electrolyte is infiltrated into interfilament interstices between the exposed lengths of the X filaments and a cathode electrode is placed in electrically conductive relation to the electrolyte to form an electrolytic capacitor.