The variation of the volume of two bituminous coals with different maximum fluidity (MF) values has been determined using carbonization tests, and the quality of coke obtained has been examined using scanning electron microscopy (SEM) micrographs. The structural and chemical changes in bituminous coals at the pre-plastic stage during carbonization were studied using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) techniques and compared to the changes in their electric and dielectric parameters. It was observed that the structural and chemical transformations occurred in the disordered phase of both coals in different ways. These differences are attributed to the different redistributions of hydrogen between the radicals generated in the aliphatic and aromatic parts of the macromolecule fragments.