The trans-1-naphthol/H2O cluster was investigated by [1 + 1] resonantly enhanced multiphoton ionization and by [I + 1'] zero kinetic energy photoelectron (ZEKE-) spectroscopy. In the electronically excited state of the cluster a bending vibration of 57 cm(-1) appears with considerable intensity and is also present in combination with several intramolecular bands. Some other intermolecular vibrations in the electronically excited S-1 state are tentatively assigned. The ZEKE-spectrum reveals a progression in the intermolecular stretch with a harmonic frequency of 190.5 cm(-1). An ionization energy of 59133 cm(-1) was determined from the ZEKE-spectrum. (C) 2003 Elsevier B.V. All rights reserved.