| Summary: | Co<sub>3</sub>O<sub>4</sub>, MgCo<sub>2</sub>O<sub>4</sub> and MgO materials have been synthesized using a simple co-precipitation approach and systematically characterized. The total conversion of toluene to CO<sub>2</sub> and H<sub>2</sub>O over spinel MgCo<sub>2</sub>O<sub>4</sub> with wormlike morphology has been investigated. Compared with single metal oxides (Co<sub>3</sub>O<sub>4</sub> and MgO), MgCo<sub>2</sub>O<sub>4</sub> with the highest activity has exhibited almost 100% oxidation of toluene at 255 °C. The obtained results are analogous to typical precious metal supported catalysts. The activation energy of toluene over MgCo<sub>2</sub>O<sub>4</sub> (38.5 kJ/mol) is found to be much lower than that of Co<sub>3</sub>O<sub>4</sub> (68.9 kJ/mol) and MgO ((87.8 kJ/mol)). Compared with the single Co and Mg metal oxide, the as-prepared spinel MgCo<sub>2</sub>O<sub>4</sub> exhibits a larger surface area, highest absorbed oxygen and more oxygen vacancies, thus highest mobility of oxygen species due to its good redox capability. Furthermore, the samples specific surface area, low-temperature reducibility and surface adsorbed oxygenated species ratio decreased as follows: MgCo<sub>2</sub>O<sub>4</sub> > Co<sub>3</sub>O<sub>4</sub> > MgO; which is completely in line with the catalytic performance trends and constitute the reasons for MgCo<sub>2</sub>O<sub>4</sub> high excellent activity towards toluene total oxidation. The overall finding supported by ab initio molecular dynamics simulations of toluene oxidation on the Co<sub>3</sub>O<sub>4</sub> and MgCo<sub>2</sub>O<sub>4</sub> suggest that the catalytic process follows a Mars–van Krevelen mechanism.
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