The relationship between zeolite acidobasic properties and hydrogen bonding in the neutral b ... HO(zeolite) and ion-pair BH+...O--(zeolite) surface complexes of acetonitrile-d(3) and pyridine, respectively, was studied using FTIR spectroscopy and at the ab initio Hartree-Fock (HF) and MP2 theory levels. Attention was also paid to the effects of coverage of zeolite-bridging DH groups. The ion-pair and neutral types df hydrogen bonds were distinguished according to their characteristic spectral behavior observed upon varying the zeolite composition and structure. In the spectra of the CD3CN ... H-O-zeolite complex, the larger acid strength of bridging hydroxyls (along the HNaX < HY < HM congruent to HZSM-5 zeolite sequence) resulted:in larger red and blue shifts of frequencies of stretching nu(OH) and bending delta(OH), gamma(OH) vibrations, respectively. This finding reflects the increase in the dissociation energy Of the neutral H-bonded complex with increasing OH acid strength. In contrast, the frequency shifts of the nu(NH) stretching vibration in the pyridine-H+...O---zeolite complex increase with the basicity of the skeletal oxygens, i.e. in the opposite zeolite sequence than for the CD3CN ... H-O-zeolite complex. This observation provides evidence for the formation of ion-pair H-bonds in pyridine/zeolite surface complexes. This conclusion is also supported by the energetics of the proton-transfer reaction calculated at the HF and MP2/DZP theoretical levels.