With more stringent CO emission limits, the development of efficient and durable catalysts for low-temperature (<200 degrees C) CO oxidation is crucial for the automotive industry. Here we report significant improvement in catalytic activity by incorporation of RuO2 into the CeO2 lattice. The Ru0.15Ce0.85O2-y demonstrates the highest catalytic activity with T-100 value of 165 degrees C (r(co) = 3.65 x 10(-5) mol g(cat)(-1) s(-1)), corresponding to activation energy of 49.8 kJ mol(-1). The TOF of Ru0.015Ce0.85O2-y (48.6 x 10(-3) s(-1)) is approximately 20 times higher than that of Ru0.015Ce0.85O2-y (48.6 x 10(-3) s(-1)) and Ru0.3Ce0.7O2-y (2.72 x 10(-3) s(-1)) catalysts at 160 degrees C. The catalyst remained stable after 70 h continuous operation under high GHSV (150000 ml g(-1), h(-1)) without any noticeable compositional and structural changes. The necessity of using CO-TPR instead of commonly used H-2-TPR analysis is presented to assess the surface reducibility of the catalysts for CO oxidation reaction. Based on the structural characterizations combined with kinetic studies, we find the catalyst surface reducibility by CO determines the activity in CO oxidation. (C) 2019 Elsevier Inc. All rights reserved.