The model reaction system F− +C2H5F + nHF (n = 0–4) has been investigated by use of a density-functional method, in order to achieve a qualitative understanding of the effect of solvation on the E2 and SN2 reactions. Two characteristic effects already occur upon monosolvation: a) the activation energies of the E2 and SN2 pathways increase significantly and even become positive, because reactants are more strongly solvated than transition states; b) the SN2 transition state is stabilized much more and becomes lower in energy than the anti-E2 transition state. This agrees with general experience from gas- and condensed-phase experiments. The solvation is analyzed from two complementary viewpoints: a) as an interaction between solvent molecules and the F−/C2H5F reaction system; b) as an interaction between the [F−, nHF] solvated base and the C2H5F substrate. The extent to which condensed-phase characteristics can be modeled by this microsolvation approach is discussed.