Density functional calculations show that reactivity of the HS- ion, if solvated by water or alcohol molecules, is fundamentally different. Irrespective of the number of surrounding solvent molecules, the hydrated ion is slightly electrophilic, whereas ion solvated by alcohol molecules is strongly nucleophilic. As the number of surrounding solvent molecules increases, the ion becomes harder, whereas nucleophility (electrophility) for the ion and constituent sulfur atom does not vary too much. The reactivity indexes for solvated HS- ions correlate with the dielectric constant of the bulk solvent. (c) 2005 Elsevier B.V. All rights reserved.