Electrical conductivity through single molecules is affected by a variety of factors, such as solvation around the molecule, connecting configuration between the molecule and electrodes, thermal fluctuation of the molecular structure, and so on. We here investigate the electrical conducting properties of several single molecules tethered to Au electrodes by means of first-principles simulations using the combined nonequilibrium Green's function/density-functional theory. The transmission probabilities computed with the explicit inclusion of solvating water molecules agree well with experiment, revealing that the effect of solvent water molecules must be accounted for in calculating the electrical conductivity through solvated molecules. (C) 2011 Elsevier B. V. All rights reserved.