A comparison was made of the bubbles formed on a horizontal bottom-facing electrode in a physical analogue model with. those formed electrolytically, Bubbles formed in a physical analogue model by forcing air through a porous plate are larger, with wetted clear areas between bubbles. In contrast, electrolytically generated gas bubbles are smaller and the electrode surface is covered with a foamy layer of tiny bubbles. To measure the bubble resistance on horizontal electrodes, a method was developed for vertical electrodes so that the measurements may be validated by comparison with published data. Voltage fluctuations were measured and analysed using fast Fourier transform (FFT). The magnitude of the bubble impedance was obtained at a superimposed a.c. frequency f(0). The phase angle caused by the effects of the double layer capacitance and the faradaic impedance on bubble resistance were determined. The effects of the faradaic impedance and the double layer capacitance were shown to be negligibly small under experimental conditions.