Co2+ ions were incorporated into the interlayer space of a layered manganese oxide film grown anodically. The film on Pt substrate was subjected to repetitive electrochemical cycling in aqueous Na2SO4 electrolyte in the potential region between 0 and +0.8 V (vs Ag/AgCl). With increasing cycle number, the voltammetric capacitance gradually increased, accompanying a drastic morphological transformation in which the multilayers lying parallel to the substrate before cycling were aligned vertically. The resulting film exhibited a high specific capacitance of 223 F/g at 2 mV/s with excellent charge/discharge stability.