This work is devoted to investigations of the influence of O-H···Se(-) hydrogen bonds on the electronic shells of selenolate R-Se(-) fragment (R═CH ₃). The geometric, energetic and nuclear magnetic resonance (NMR) spectral parameters for various conformers of CH ₃Se(-)-(H ₂O) _n clusters with n = 0–6 were calculated at CCSD/aug-cc-pVDZ level of theory. For selenolate anion CH ₃Se(-) solvation free energy was calculated, and for water media it is equal to −71.41 kcal/mol. For O-H···Se(-) hydrogen bonds the proportionality coefficients between QTAIM parameters at (3; −1) bond critical point and the strength of an individual hydrogen bond ∆E were proposed. It was shown, that despite a relative weakness of O-H···Se(-) hydrogen bonds, the outer electronic shell of the selenium atom changes significantly upon formation of each hydrogen bond. This, in turn, cause the dramatic change of NMR parameters of selenium nuclei.