We report the vibrational predissociation spectrum of the NO-.H2O complex in the OH stretching region. The ionic H-bonded OH stretch is much less red-shifted and less structured in the vibrational spectrum of NO-.H2O than in that of the O-2(-).H2O cluster, despite the larger proton affinity of NO- relative to O-2(-). It is argued that the differences between the spectra of these two species are primarily a consequence of the greater charge-transfer character in the O-2(-).H2O cluster and that the charge-transfer component is much less important in NO-.H2O because of its triplet spin character.