Currently, the study of the chemical structure of coal has become a fundamental issue of coal chemistry and has caught the attention of coal researchers. To study the chemical characteristics and coal structure of the Steenkool cooking coals in the northern part of the Bintuni Basin, West Papua; Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD), have been used. FTIR measurement shows that the coal samples contain a high fraction of poly-aromatic moieties and the saturated long-chain contains high levels of hydrocarbons. Fourier transform infrared spectroscopy spectra reveal the presence of the aromatic, aliphatic, and oxygen-containing functional groups. The more mature the coal, the more aromatic compounds were found than the aliphatic and oxygen compounds; indicating a relationship between the functional group and the degree of coalification. A turbostratic arrangement of carbon crystal structures that are less than disordered amorphous carbon was present in the coals and was determined by XRD. The XRD investigations showed a good correlation between the calculated maturity structural molecular parameter (aromaticity, I26/I20), and the vitrinite reflectance maturity of the coals.