The catalytic oxidation reaction of CO has recently attracted much attention due to potential applications in the treatment of air pollutants. The development of inexpensive transition metal oxides catalysts that exhibit high catalytic activities for CO oxidation is in high demand. However, these metal oxide catalysts are susceptible to moisture, as they can quickly be deactivated in the presence of trace amounts of moisture. This Article reports a facile synthesis of highly active Co3O4@CNT catalysts for CO oxidation under moisture-rich conditions. Our synthetic routes are based on the in situ growth of ultrafine Co3O4 nanoparticles (NPs) (~2.5 nm) on pristine multi-walled CNTs in the presence of polymer surfactant. Using a 1% CO, 2% O2 balanced in N2 (normal) feed gas (3-10 ppm moisture), a 100% CO conversion with Co3O4@CNT catalysts was achieved at various temperatures ranging from 25 to 200 oC at a low O2 concentration. The modulation of surface hydrophobicity of CNT substrates other than direct surface modification on the Co3O4 catalytic centers is an efficient method to enhance the moisture resistance of metal oxide catalysts for CO oxidation. After introducing fluorinated alkyl chains on CNT surfaces, the superhydrophobic Co3O4@CNT exhibited an outstanding activity and durability at 150 oC in the presence of moisture-saturated feed gas. These materials may ultimately present new opportunities to improve the moisture resistance of metal oxide catalysts for CO oxidation.