The first part of this paper presents generalities on molecular ozone reactivity. The second part focuses on catalytic ozonation with the objective to evaluate the efficiency of such an AOT versus ozonation alone. The literature data relative to catalytic ozonation concerns either the activation of ozone with metals in solution, or the heterogeneous behavior of solid catalysts. Numerous metals (Fe, Mn, Ni, Co, Zn, Ag, Cr) under various forms (salt of reduced metal, solid oxide, deposited metal on support) were reported to enhance the efficiency of ozone towards the removal (or the conversion) of different organic compounds in aqueous solution. Some years ago, heterogeneous catalytic ozonation has begun to be studied in our group. This paper presents a short synthesis of the main results obtained, illustrated by three different experimental procedures which can be used to test catalytic ozonation. Finally, some hypothesis on reaction mechanisms and prospects are examined.