A series of copper-promoted platinum supported on activated carbon (Cu-Pt/AC) catalysts were investigated for glycerol oxidation to lactic acid. The catalytic performance of 1.0%Pt/AC catalyst was greatly influenced by Cu loading (0.1-2.0 wt%). Among them, the 0.5%Cu-1.0%Pt/AC catalyst showed the best promotional effect, whose lactic acid yield was 2.4 times of that on 1.0%Pt/AC under same reaction conditions. Characterizations were carried out to explore the relationships between catalyst properties and reaction performances. TEM images show that the introduction of Cu improves the dispersion of Pt and Cu, and some Pt-Cu interfaces are detected by HR-TEM, which would facilitate the glycerol transformation. XPS and H2-TPR analyses reveal that good catalyst performance is related with not only a proper surface Pt/Cu molar ratio, but also copper species' oxidation states. Cu+ and Cu-0 species favor glycerol conversion and lactic acid production, whereas large CuO particles facilitate the formation of glyceric acid. (C) 2016 Elsevier B.V. All rights reserved.