The effects of two kinds of surface modifications (chemisorption and electrochemical modification) on the adsorption of methanol and atomic oxygen on Ag(110) surface have been investigated using B3-LYP method with cluster models. The promotion effect of halogen atoms was found to be mainly electrochemical. Both modifications. either by chemisorption of halogen atoms or by the presence of -q/ + q point charges. increase the work function of the Ag(110) surface. Strong correlation between the adsorption energy of methanol, as well as atomic oxygen and the work function change induced by the two kinds of modifications has been found, (C) 2002 Elsevier Science B.V. All rights reserved.