Provided is a composite electrode including a metal layer and a composite dielectric layer. The composite dielectric layer includes a metal oxide dielectric layer and a polymer dielectric layer. The composite dielectric layer overlays the metal layer. The polymer dielectric layer includes a nitrogen-containing polymer and overlays the metal oxide dielectric layer. An electrolytic capacitor is also provided. The electrolytic capacitor has a polymer dielectric layer made of a nitrogen-containing polymer, and such polymer dielectric layer is beneficial to increase the insulating property of the metal oxide dielectric layer and the coverage property of the conductive polymer. Thereby, the conventional leakage current can be significantly reduced and the yield can be improved.