Acid-base bifunctional catalysis can be categorized into two types; a type in which acid and base interact simultaneously with the substrate, and a type in which acid and base interact successively with the substrate and the transformed substrate. The former simultaneous interaction of acid and base can be further categorized into two parts; a part in which both acid and base interact with the same substrate molecule in concerted manner (concerted mechanism), and a part in which acid and base interact independently with different molecules (go-together mechanism). Acid catalyzed reactions are greatly affected by addition of base into the reaction system. Addition of base can be categorized into two types too; one in which base is doped on the catalyst to modify the acid-base properties of the catalyst (static doping), and one in which base is doped in the substrate to modify the catalytic action during the reaction (dynamic doping). Several recent industrial processes are reviewed along these categorizations and it appears that acid-base bifunctional catalysis has a great impact on designing industrial technologies. (C) 2006 Elsevier B.V. All rights reserved.