The catalytic performance of the supported Co3O4 on CNTs (Co3O4/CNTs) in the catalytic combustion of toluene was improved by tuning the surface structures of CNTs. The study results showed that the surface defect structures of CNTs could not only enhance the ability of Co3O4 to develop reduction/oxidation cycles, but also increase the proportion of the adsorbed oxygen species to the surface lattice oxygen ones. Thus, the defects of CNTs could improve the catalytic activity of Co3O4/CNTs and lower the complete conversion temperature of toluene. Moreover, the CO2 selectivity increased along with increasing the -COOH amount of the CNTs. Therefore, by tuning the defect density and -COOH amount, the conversion of toluene was completed at 257 degrees C and the selectivity to CO2 achieved to similar to 100% on Co3O4/CNT5-120 catalyst, which is much better than Co3O4/Beta, Co3O4/ZSM-5 or Co3O4/SBA-15. Furthermore, compared with Pd/Beta and Pd/SBA-15 catalysts, Co3O4/CNTs showed a similar or even better catalytic performance, indicating the great potential application of Co3O4/CNT catalysts for the catalytic combustion of toluene. (C) 2013 Elsevier B.V. All rights reserved.