For an accurate estimate of the specific capacitance it is imperative that the mass of active material be known. This is of particular importance for thin films of electrodeposited manganese dioxide, where the conventional determination of active material is not possible. Here we compare three indirect methods of mass analysis; namely, by integration of chronoamperometric i–t data, through the use of the electrochemical quartz crystal microbalance, and via manganese analysis of the deposit via ICP-OES. Each of these approaches was shown to be complicated by a range of experimental artefacts; however, it was concluded that the integration method was the preferred approach because of its focus only on the electroactive manganese species within the electrode.