Hydrogen bubble formation on the surface of platinum electrodes as a means of removing biofilms was studied. Biofilms of Pseudomonas fluorescens of different ages were grown on platinum electrodes and challenged with hydrogen bubbles formed at the surface of the electrodes, by cycling the potential at -2.0 V. The removal of the biofilms from the surfaces was assessed by direct epifluorescence microscopy. The removal of the biofilm from the surface was dependent on the biofilm age. As the biofilm became older, the duration of bubble formation needed to achieve complete removal changed, but in some cases, it was not possible to obtain a completely clean surface. An enhancement of biofilm removal was obtained if the potential was cycled between -0.5 and 1.0 V for 30 min prior to bubble generation, probably due to the weakness of the forces established between the surface and the biofilm and within the biofilm. (c) 2004 Elsevier Ltd. All rights reserved.