Abstract: The temperature-dependent IR spectra of o-ethoxy benzole acid reveal that the inter-molecular structure patterns in the liquid state are basically the same as those in the solid state close to its melting point, which exist in the form of intramolecular H-bonding.But at - 150℃ the characteristic carboxyl dimer absorptions were observed, whose intensities increase with the fall of temperature.Their OHvibrations were proved by the spectra of C₂H₅OC₆H₅COOD and C₂H₅OC₆H₅COCl.

Key words: Low temperatrue IR spectra, o-ethoxybenzoic acid, H-bonding