The SMD implicit solvation model augmented with one and four explicit water molecules was used to calculate pK(a)'s and redox potentials of N-methyl-substituted nucleic acid bases guanine, adenine, cytosine, thymine, and uracil. Calculations were tarried out with the B3LYP/6-31+G(d,p). level of theory. The same numbers of water molecules were hydrogen bonded to the neutral, protonated, and deprotonated nucleobases in their unoxidized and oxidized forms. The improvement in pK(a1) involving neutrals and cations was modest. By contrast, the improvement in pK(a2) involving neutrals and anions was quite significant; reducing the mean absolute error from 4.6 pK(a) units, with no waters, to 2.6 with one water and 1:7 with four waters. For the oxidation of nucleobases, adding explicit waters did little to improve E(X-center dot, H+/XH), possibly because both species in the redox,couple are neutral molecules at pH 7.