Goonyella coking-coal was extracted with a 1:1 (v/v) carbon disulfide/N-methyl-2-pyrrolidinone (CS2/NMP) mixed solvent and then fractionated into four with pyridine and chloroform. High temperature H-1 NMR analysis conducted on each fraction and their mixtures in-situ showed that the lightest, the chloroform-soluble fraction (CS), was rich in mobile hydrogen, H, the variation of which with temperature corresponded to that of a thermoplastic parameter tan 6 determined by in-situ viscoelastic measurement. In contrast, chloroform-insoluble and pyridine-soluble (CIPS) and pyridine-insoluble (PIMS) fractions showed scant change in H. with temperature, although the intermediate hydrogen, H-int, increased upon heating. These results allow the different fractions to be characterized qualitatively on the basis of differences in hydrogen mobility. In mixtures of the continuous fractions, positive interactions occurred that enhanced the value of tan 6 as well as the overall hydrogen mobility. A single maximum was observed in the tan 6 response of these mixtures, which indicated that the heavier fractions were solvated through the action of the lighter ones. In a discontinuous mixture of the fractions, molecular interaction was slight compared to continuous mixtures; only the light fraction started to soften at low temperature and, as a result, a bimodal response occurred in tan delta. The thermoplastic response of coking coal can be modeled on a self-dissolution basis involving the similar to50% of solvent-soluble components that are present in whole coking coals and which possess a continuous fraction distribution from light to heavy. The mobility of the system develops continuously upon heating as a result of the progressive solvating action of the lighter components facilitating dissolution and/or dispersion of the heavier components.