Consequently, manganese oxide surfaces have been found to expose metal (Mnⁿ⁺), oxide (O^2-) and defect sites of various oxidation states, degrees of coordination unsaturation and, thus, acid and base properties. Furthermore, the d-d electron exchange interactions between intimately coupled manganese ions of different oxidation states [Mnⁿ⁺-O-Mn⁽ⁿ⁺¹⁾⁺] furnish the electron-mobile environment necessary for the surface redox activity. It is these diverse structural and electronic properties that shape-up the surface attributes of the long known redox catalytic activity of manganese oxides.

The present article was designed to review, assess and correlate results of research studies performed in these and other laboratories, focusing on the mechanistic aspects of redox catalysis on manganese oxides. Reactions of environmental and technological importance, such as oxidation of CO and light hydrocarbons, decomposition of H₂O₂ and O₃, oxidative coupling of CH₄, and selective reduction of  NO_x, are  brought  into prominence. Proposed mechanisms for these reactions are summarized and assessed. Ultimately, the present review aims at highlighting the surface attributes of redox catalysis on manganese oxides.