Electrodeposition will prove to be promising for the preparation of magnetic metal nanostructures. Multilayered fcc Co/Pt nanostructures grown on a Pt(lll) single-crystal substrate by electrodeposition under potential control exhibit a remanent perpendicular magnetization and a large magnetic coercivity, which depend on the multilayer growth mechanism. A possible interfacial alloying below the Pt overlayers induces a magnetic moment on the Pt atoms, leading to asymmetry between Pt/Co and Co/Pt interfaces of the multilayers. The role of the codeposition of Ni as an inhibitor for the nucleus growth process as well as for the dissolution of Co during the Pt deposition is of great importance for the occurrence of the multilayered nanostructure.