CD 2Cl 2 solutions of four trans-retinal Schiff base (containing methylamine, n-butylamine, t-butylamine and 5-butyl-nonylamine), their perchlorates and their 1:1 complexes with 3,4-disubstituted and 4-monosubstituted phenols were studied as a function of temperature using Fourier transform infrared (FTIR) spectroscopy. The thermodynamic quantities Δ H 0 F and Δ S 0 F of hydrogen-bond formation and Δ H 0 PT and Δ S 0 PT of the proton transfer process across the hydrogen bonds were determined. All (I) OH⋯N⇌O −⋯H +N (II) bonds show large proton polarizability as indicated by continua in the IR spectra. In all the systems studied, the Δ H 0 PT and Δ S 0 PT values of the (I) OH⋯N⇌O −⋯H +N (II) equilibrium were negative. This is a result of the highly ordered arrangement of the solvent molecules around these complexes. Δ H 0 F and Δ S 0 F of formation of the OH⋯N⇌O −⋯H +N bond and Δ H 0 PT and Δ S 0 PT decrease significantly with decreasing acidity of the phenol. Furthermore, Δ H 0 PT and Δ S 0 PT decrease significantly with increasing screening of the hydrogen bonds from the solvent environment by bulky groups. This indicates that the Δ H 0 PT and Δ S 0 PT values are determined by the interaction of the hydrogen bonds with their environment.