Stable catalysts prepared by dispersing Cu2O nanoparticles on activated carbon were investigated in the oxidative carbonylation of methanol to dimethyl carbonate. The effect of the surface oxygen containing groups (OCGs) on the rate of dimethyl carbonate formation and the selectivities of the catalyst for dimethyl carbonate and the byproduct methyl formate were determined. The carbon support surface OCGs played a key role in the oxidative carbonylation. For carbon supports with the same amount of OCGs, the highest catalytic activity was achieved at a certain level of Cu loading. The optimal Cu loading as well as catalytic activity increased linearly with the amount of OCGs. The active sites of the catalysts were the Cu2O nanoparticles that coordinated to the OCGs on the carbon surface.