The aim of the present study was to evaluate the effect of neutralizing the OH- electrogenerated during bipolar membrane electroacidification (BMEA) on the integrity of the cationic and bipolar membranes used. The OH- were neutralized by acidification of the anionic side compartment of the bipolar membrane during BMEA of skim milk. The integrity of the membranes was characterized by membrane parameters and microscopic membrane surface elemental analysis and mapping. It appeared from these results that the resistance of cationic membranes increased, due to an exchange of monovalent counter-cations of the membrane by divalent cations less mobile and to a slight protein fouling. However, integrity and physical characteristics of bipolar membranes were preserved during BMEA. (C) 2003 Elsevier Science B.V. All rights reserved.