The solvent extracts of Upper Freeport and Illinois No.6 coals were mixed with N-methyl-2-pyrolidinon (NMP) and annealed at 353K to produce the gelatinous materials. Differential scanning calorimetric measurements revealed that the materials can hold significant amounts of nonfreezable NMP (as much as 3g NMP per 1g coal extracts) which disperse in the materials on a molecular scale, indicating the materials are not phase separated. The thermal behaviors were measured macroscopically as a function of the extract concentration using a needle penetrometer during heating from 223 to 360K. The penetration–temperature curves were analyzed to estimate the apparent viscosity (η a ). During the penetrations, η a was decreased very rapidly, approximately four orders of the magnitude by a temperature increase of 20K, suggesting that the coal extracts-NMP mixtures undergoes a gel to sol transition. The heats of dissociation of crosslinks (ΔH m ) were estimated by applying Eldridge–Ferry equation. The ΔH m of coal extracts-NMP mixtures was relatively small, i.e. approximately 10kJ/mol, whereas the ΔH m of polyvinyl alcohol-NMP gel in which the hydrogen bonds contribute the formation of the physical network structures, was about 65kJ/mol. Not the specific interaction such as hydrogen bonds, but weak interactions such as van der Waals force were likely to contribute the formation of the coal extracts-NMP gel.