Recently, the authors have presented a new method to estimate the strength distribution of hydrogen bonds (HBD) in coal. The method analyzes the IR spectra ranging from 2400 to 3700 cm(-1) that are obtained using an in-situ diffuse reflectance IR Fourier transform (DR) technique with neat, undiluted coal samples. Each spectrum was divided into six hydrogen bonded absorption bands by a curve-resolving method; then the amount of hydroxyls contributing to each hydrogen bond was estimated by Beer's law with different absorptivity for each band. The strength of each hydrogen bond was estimated using a relation presented by Drago et al. that is known as one of the "linear enthalpy-spectroscopic shift relations". In this paper, the method was applied to estimate the hydrogen bond strength distributions formed between coal and several polar solvents: acetone, ethyl acetate, THF, DMF, and pyridine. The enthalpies accompanying the adsorption or desorption of the solvents, which correspond to the heats of adsorption, were also estimated from the HBDs. Only IR spectra measurements were found to be enough to obtain such enthalpies. This greatly simplified the calculation procedure and increased the accuracy of the enthalpies. The validity of the proposed in situ IR measurement method and the analysis method for obtaining HBD was well clarified by comparing the enthalpies obtained in this work with the heats of adsorption and the hydrogen bond formation enthalpies proposed by Arnett et al.