The hydrogen bonding between benzonitrile and one and two water molecules is studied ab initio by means of a hybrid B3LYP density functional in conjunction with 6-31+G(d,p) and aug-cc-pVDZ basis sets. The strength of such hydrogen bonding is analyzed in terms of a magnitude of "window region" appearing in the infrared spectra of the studied complexes and experimentally measurable and also in terms of the shifts of the stretching mode of the triple CN bond of benzonitrile. The lower-energy portions of the potential energy surfaces in the neighborhoods of the stable complexes of benzonitrile with one and two water molecules are fully determined, and implications of their landscape on the large-amplitude dynamics of the water moiety around benzonitrile and comparison with experiments are elaborated.