The surface area of RuO2 electrodes was evaluated through the analysis of the potential transients obtained when the equilibrium potential of the quinone/hydroquinone redox couple is perturbed with a periodic current signal of low amplitude. Under these conditions, the behaviour of a smooth electrode is equivalent to that of an RC circuit. The applicability of this method to the RuO2 electrodes characterised by a highly porous structure was demonstrated. The optimum ranges of frequencies and current amplitudes were determined. The accuracy of the proposed method was verified through the independence of the calculated surface area on the type of current signal as well as on the current amplitudes.