An X-ray diffraction (XRD) technique has been applied to the study of asphalt binders. XRD patterns were obtained using a Rigaku DMax 2200 V-PC (personal computer). Jade software (version 6.1) was used to perform the peak search, full width at half maximum, and profile fits with Pearson VII and pseudo-Voigt mathematical functions over the areas of interest The XRD spectra were also modeled in Mathematica using a generalized Fermi function (GFF). Analysis shows a mixed correlation in the data in terms of mathematical fit, analysis of fit, and plotting. Aromaticity and crystallite size parameters were calculated for the asphalt binders using the data from the three functions (Pearson VII, pseudo-Voigt, GFF). Results are compared and discussed with respect to aging effects, asphalt binder models (Yen, Yen-Mullins), and fuel technology.