IR photodissociation (IRPD) spectra of [(N2O)(n)H2O](+) with n = 2-7 are measured in the 1100-3800 cm(-1) region. The IRPD spectra show the v(1) and v(3) vibrations of the N2O components at around 1250 and 2200 cm(-1) and the OH stretching vibrations of the H2O part in the 2400-3800 cm(-1) region. In the OH stretching region, the IRPD spectrum of the [(N2O)(2)H2O](+) ion shows a sharp band at 3452 cm(-1) and a broad one at similar to 2700 cm(-1), which are assignable to the stretching vibrations of the free and hydrogen-bonded OH groups, respectively. The IRPD spectrum of the [(N2O)(3)H2O](+) ion displays no band of the free OH stretching vibration; the solvent N2O molecules are preferentially hydrogen-bonded to the OH groups. In parallel, the geometry optimization and the vibrational analysis are carried out at the B3LYP/6-311++G(d,p) level of theory. Comparison of the IRPD spectra with the calculated IR spectra suggests that the [(N2O)(n)H2O](+) cluster ions have an (N2O center dot H2O)(+) ion core, in which the positive charge is delocalized over the H2O and N2O components and that an intermolecular semicovalent bond is formed between the oxygen atoms of H2O and N2O through the charge resonance interaction. In the clusters larger than n = 3, two solvent N2O molecules are strongly hydrogen-bonded to the OH groups, and the other ones are weakly bound to the ion core. The band position of the v(1) vibration of the solvent N2O molecules suggests that the oxygen end of the solvent molecules is bonded to the ion core.