[en] The interaction of CO with solid surfaces is a topic of fundamental and applied interest. Nowadays there is an increasing attention on alternative energy carriers, like efficient in situ conversion of methanol to hydrogen. There are several studies in the literature about the catalytic activity of Pd and Rh for dehydrogenation of liquid methanol. It was also shown, that the Cu-ZnO, Pd-ZnO catalysts show a high activity for the dehydrogenation of methanol. At the same time these systems can also be used to catalyze the hydrogenation of CO and CO₂ to form methanol. In this work we performed theoretical calculations of 0.75 ML CO coverages on the Pd(111) and Pd(111)-Zn systems. The adsorption of CO on noble metals was already studied using STM techniques. Using the DFT techniques we can calculate the STM images so, we can delineate the detailed structure of the surface alloy films