Hydrated structure of Nph(-)(H2O)(2) was investigated using infrared (IR) spectroscopy. Among OH stretching vibrations, three pi-hydrogen bonds to anionic naphthalene ring, namely ionic pi-hydrogen (ipiH) bonds, and an interwater hydrogen bond were observed. It allowed us to elucidate the geometrical structure of Nph(-)(H2O)(2). The unstable naphthalene bare anion was stabilized through the ipiH bonds with the water dimer on its ring, forming the one-sided structure. Besides, the intensity of the aromatic CH stretching modes was found to be enhanced upon the electron attachment without significant lowering of their frequencies. (C) 2003 Elsevier Science B.V. All rights reserved.