Thermogravimetry analyses have been employed to study the catalytic effect of different metal oxide nanoparticles on the thermo-oxidative decomposition of asphaltenes at isothermal conditions. Three metal oxide nanoparticles were considered in this study, namely: NiO, Co3O4 and Fe3O4. Results showed that the presence of nanoparticles decreased the activation energy of asphaltenes oxidation and enhanced the reaction rate. It appears that the thermo-oxidative reaction is metal oxide specific. The obtained kinetic data showed that NiO has the highest reaction rate followed by Co3O4 and then Fe3O4, which suggests a change in the reaction mechanism. (C) 2012 Elsevier B. V. All rights reserved.