The reforming of methane with carbon dioxide has been investigated at 773 K on 10% Co/Al2O3 reduced at different temperatures up to 1173 K. The catalysts were characterized by BET, TPR, XRD and XPS methods. TPR and XPS results revealed that during the pre-treatment of the catalysts the Co only partially reduced. The reduction degree and the amount of the structured metallic cobalt increased with the reduction temperature. The conversion of the reactants was the highest on the sample reduced at 973 K, but the turnover frequencies of CO and H-2 formation increased as the reduction temperature increased. The amount of surface carbon significantly depended on the pre-treatment temperature of the catalysts. The IR spectra registered at the beginning of the reaction indicate that tilted CO was formed, but the position of the absorption bands depends on the reduction temperature of the catalysts. Similarly, the pre-treatment temperature influenced the type of the surface carbon determined by XPS. We assume that the different structures of the metallic Co formed in pretreatment resulted in the different catalytic behaviors. (C) 2016 Elsevier B.V. All rights reserved.