The mid-IR vibrational spectrum of the strongly bound F-. H2O complex is reported via predissociation of the size-selected F-. H2O . Ar-m (m = 1-3) clusters. A weak, sharp band at 3690 cm(-1) confirms that this species adopts the asymmetric arrangement typical of the heavier halides, while the band arising from the ionic H-bond (IHB) is shifted very far to the red of the free H2O bands (shift similar to 800 cm(-1)). The observed band position is actually found in the region of the predicted 'overtone' of the H-bonded oscillator, where the OH stretching vibration occurs in a very strongly anharmonic O-H ... F-potential surface in which the first excited vibrational level samples the HF-OH- proton transfer configuration.