We report a novel silica co-electrodeposition route to prepare nanostructured MnO2 films. Firstly, MnO2-SiO2 composite film was fabricated on a stainless steel substrate by potentiodynamical deposition, i.e. cyclic deposition, and then the SiO2 template was removed by simple immersion in concentrated alkaline solution, leading to the formation of a porous MnO2 (po-MnO2) matrix. The structure and morphology of the obtained films were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical properties of the po-MnO2 film were evaluated by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS). Results showed that this porous MnO2 derived from the MnO2-SiO2 composite film exhibits good electrochemical performance for potential use as a supercapacitor material.