Respirable dust does great harm to human health. In this paper, we focused on the wetting characteristics of respirable coal dust, and the effect of functional groups of respirable coal dust on its wettability was investigated. We selected five different types of coal samples (Lignite, Gas fat coal, Coking coal, 1/3 Coking coal, and Anthracite) from some typical mining areas in China. We used a Fourier Transform Infrared Spectrometer (FT-IR) to obtain the IR spectrum of the respirable coal dust, and the percentage of functional groups for each respirable coal dust was obtained by the peak area normalization method and then analyzed. And the wettability of respirable coal dust was evaluated by contact angle measurement. It is found that the benzene rings, aromatic hydrocarbons with benzene rings, aliphatic hydrocarbons with methyl, methylene, and so on, which have carbon-containing macromolecular structures, are hydrophobic. While the oxygen-containing functional groups represented by hydroxyl and carboxyl groups, and silicates and carbonate minerals are hydrophilic. Besides, the results show that respirable coal dust of different metamorphic grade coals has different wettability. This study has important theoretical significance for understanding the wettability of respirable coal dust. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.