The deconvolution and resolution of overlapping bands in the Raman spectra of a suite of coals studied by curvefitting methods has improved our understanding of the main structural changes in naturally matured coals. Even though much work on deconvolution of Raman spectra has been done, the systematic evolution of chemical structures is not well established. In this study we used a suite of 28 coal samples from Australia with vitrinite reflectance ranging from 0.38 to 3.52%. The micro-Raman spectra of vitrinite macerals from selected coals were acquired using a custom-made Raman spectrometer and supplemented by other Raman spectra previously acquired under the same experimental conditions. In the spectral deconvolution procedure, the second derivative curve-fitting method was used to determine the number of peaks and peak positions of the Raman spectra. Each band was tentatively assigned to a corresponding chemical structure by references to the interpreted major structural changes likely to have taken place during coalification. These parameters included P-D (the position of D band), RBS (the distance between G band and D band), FWHMG (full width at half maximum of G band), I-G/I-GL (the intensity ratio of G band and G(L) band), and A(R)/b (the ratio of Raman integrated area and the slope of the spectral background). All of these Raman parameters are found to have a very good correlation with Ro% with R-2 higher than 0.90. While five simple equations have been proposed and may be used to estimate thermal maturity of coals, two equations (Eq. (4) for Ro% from 0.38 to 1.5 and Eq. (5) for Ro% from 1.5 to 3.52) are best suitable to predict thermal maturity of coals with the most accuracy.