Five of the most important Colombian coals were studied using Photoacoustic Fourier transform infrared (PA-FTIR) spectroscopy. The PA-FTIR spectra were used to obtain structural parameters and to determine the analytical potential of this technique. The molecular structural parameters, CH(2)/CH(3,) f(a), H(al)/H(ar), and (R/C)(u) were correlated with fixed carbon contained in the samples to determine aliphatic hydrogen, H(al), and the aromatic hydrogen, H(ar) in coals studied here. These parameters enabled the determination of aromaticity, f(a), which was found to be between 0.66 and 0.98. The aliphatic and aromatic regions were considered between 3005-2760 cm(-1) and 912-670 cm(-1), respectively. Finally, using the molecular structural parameters, the grade of maturation (rank) of coal samples studied was determined. (C) 2011 Elsevier B.V. All rights reserved.