Excess infrared (IR) absorption spectroscopy, a new concept brought forward by applying the idea of excess thermodynamic functions to infrared spectroscopy, is shown to be a potential method to study hydrogen bonds. It can be applied to enhance spectral resolution of complexed IR bands, to evaluate nonideality of liquid mixtures, and to estimate selective molecular interactions. The sign of the excess infrared absorption coefficient is also of importance in providing information on molecular interactions. The results demonstrate that excess infrared absorption spectroscopy can unveil new information on hydrogen bonding in condensed phases.