The evolution regime of electrolytically generated hydrogen bubbles in acidic medium has been studied by means of spectral analysis. A stochastic model of the time series displayed by the electrolysis current during bubble evolution has been devised. The identification of the characteristic parameters of the evolution regime (nucleation rate, life time etc.) has been performed through the measured power spectral density. This analysis has been applied to the determination of the dissolution current of an iron electrode in sulphuric acid medium.