These studies are focused on understanding the role played by a solvent in chemical and electronic processes occurred in the course of semiconductor surface passivation at semiconductor/electrolyte interface. It is shown that the chemical reactivity of the ionic adsorbate at a semiconductor/electrolyte interface can be changed considerably through interaction with solvent molecules. The reactivity of anions depends essentially on the solvating solvent: hydrated ions could be either slightly electrophilic or slightly nucleophilic, whereas the ions solvated by alcohol molecules are always strongly nucleophilic. Mechanism of interaction of such solvated ions with the semiconductor surface atoms depends on the solvent, as is demonstrated by the example of processes occurred at GaAs(100)/sulfide solution interfaces. It is found that on adsorption of HS ions from different solvents the As-S bonds with solvent-dependent ionic character are formed on a GaAs(100) surface. The surface obtained in such a way possesses different ionization energy and exhibit different electronic properties dependent on the solvent. (C) 2008 Elsevier B. V. All rights reserved.