The contribution concerns the crucially important layer near the catalyst surface (here, called Z* for convenience) that turns out to be often thicker than usually assumed. Special experiments [M. Alifanti, J. Kirchnerova, B. Delmon, D. Klvana, Appl. Catal. A 262 (2004) 167] indicate that Z* could possess electrochemical features, more precisely promote polarization effects. Measurements of thermodynamical activity and introduction of foreign species in Z* could lead to progress in fundamental interpretations. Examples are given and suggestions made, concerning the use of polarizable dopes in the gas phase or in the catalyst (possibly containing two or several phases), or the application of physical activation techniques. Some speculations are proposed concerning new advances. (C) 2006 Elsevier B.V. All rights reserved.