The aim of this paper is to investigate the combined influence of H-2 bubble evolution and forced convection on the impedance of Pt in NaOH and NaOH + K-3[Fe(CN)(6)] solutions. Results have shown that bubble evolution did not disturb measurements so that the impedance technique was appropriate for investigating gas-evolving electrodes. At strong bubble evolution, the overall process was qualitatively the same in both electrolytes. without mass-transport limitations. regardless the presence of ferricyanide. However, mass-transport controlled processes appeared in some conditions. depending on the electrode rotation speed and current density which had opposite effects on bubble evolution. In these intermediate conditions in which bubble evolution was not strong enough to continuously renew the diffusion layer, but enhanced mass transfer. two new loops appeared in the Nyquist impedance diagram. The interface was modeled by considering that ferricyanide reduction occurred on Pt active sites not blocked by adsorbed hydrogen or bubbles. Simulated and experimental curves were in good agreement.