Notions about charge transfer during adsorption of anions on metals in aqueous solutions are rendered. The role played by the electron tunneling on macrocontacts during the signal formation in the method of contact electroresistance (CER) is considered. It is shown that CER depends on the metal surface coverage by adsorbed species and their effective charge. Bell-like CER vs.E curves are obtained for copper, silver, and gold in solutions containing halide ions. Potentials of maximums in the curves,E max, correspond to the charge transfer onset and depend on the nature of the metal and anion and on the anion concentration. AtE belowE max, halides adsorb in the form of ions, involving no substantial charge transfer. At potentials exceedingE max by 0.1 to 0.2 V, practically complete charge transfer occurs. With changing anion nature,E max for a given metal rises in the series I- < Br- ≪ Cl-. For a given anion (say, I-),E max increases with the metal nature in the series Cu ≤Ag ≪ Au. The link between the charge transfer during adsorption of anions and the surface reconstruction in single-crystal electrodes is discussed.