Coals of different ranks were heat-treated at temperatures up to 300degreesC in the aprotic dipolar solvent N-methyl-2-pyrrolidinone (NMP) with addition of lithium halides (LiCl, LiBr, and LiI). The treated products were extracted using a carbon disulfide/NMP (CS2/NMP) mixed solvent (1/1 by vol), and the dissolution yields were determined from the weight of the insoluble material. Addition of small amounts of lithium halides to CS2/NMP mixed solvent was reported to enhance the room-temperature extraction yields for some high-rank coals, while little effect was observed for low-rank coals (Energy Fuels 2001, 15, 141). On the other hand, in the present study, heat treatment in the presence of LiCl showed a greater effect on dissolution for low-rank than for high-rank coals. For low-rank Banko 97 coal (%C:70.0%), the dissolution yield was increased by 41.4% at 300degreesC, from 50.4% in NMP alone to 91.8% with the addition of 2.4 mmol/g-coal LiCl, and the increased dissolution yield was attributed mainly to an increase in the amount of the heavy fraction; CS2/NMP-soluble and THF-insoluble (TIMS). Furthermore, the temperature of heat treatment (175-300degreesC) and the quantity of LiCl added (0.6-3.6 mmol/g-coal) markedly affected the dissolution yield. When different lithium halides were used, the dissolution yield was increased in the order Cl- > Br- > I-; higher charge density of the anion of the additive was associated with higher dissolution yield. The mechanism of the observed effect of addition of LiCl on coal dissolution is discussed.