During the last decade, the electro-hydrodynamic (EHD) impedance method has undergone many improvements from both the theoretical and instrumental points of view. This technique was applied successfully to electrodissolution, corrosion, corrosion protection, electrocrystallization, biofilm and calcareous deposit characterization. More recent developments were achieved in our group in the case of a CE mechanism or when a mediation reaction proceeds at a conducting polymer modified electrode. This paper provides a survey of the extended potential of this method illustrated by a few examples taken from the above listed topics. (C) 2004 Elsevier B.V. All rights reserved.