The hydrogen bonds in four coals with different rank and different sulfur content were checked using the in situ diffuse reflectance FTIR (DRIFT) method. Besides the hydrogen bonds formed by −OH and −COOH groups, there exists a new kind of hydrogen bond (SH−N) formed by the −SH in the thiophenols or mercaptans and the nigrogen in pyridine-like compounds in coal. The absence of this shoulder peak in the IR spectra of low rank coals (even high sulfur) can be attributed to the high content of −COOH groups, and consequently the strong and broad absorbance in carboxylic acid dimers in this range covers the weak absorbance of SH−N. However, when the low rank coals were heated to 620 °C in Ar atmosphere and the −COOH disappears, the peak of SH−N clearly occurs. To summarize all the work on this new hydrogen bond, we assign it to the position of about 2514 cm-1.