The charge transfer through chemisorbed molecules has been studied by using normally oriented pyridine and benzoate molecules, chemisorbed on the Cu(110) surface. They yield H+ ions from the outer three C-H bond locations when ionized by electron impact. The local yield of these H+ ions allows the determination of the rate of electron transport through the molecule from the molecular contact point to the ionization position, causing ion neutralization. A superexchange (molecule-assisted tunneling) electron transfer process is found to control the electron-transfer event. (c) 2005 Elsevier B.V. All rights reserved.