Ashless coals (HyperCoal) produced by thermal extraction of coals of different ranks with 1-methylnaphthalene at temperatures from 300 to 420 degrees C for 60 min were characterised. HyperCoal has many light components that are easily volatised and decomposed, and it has high thermal reactivity. All the HyperCoals showed high thermoplasticity during heating; in particular, HyperCoals obtained from low-rank Pasir and Mulia coals showed high thermoplasticity beginning at temperatures near 150 degrees C. On increasing the extraction temperature for Pasir sub-bituminous coal, the weight loss during heating decreased and the resolidification temperature shifted to higher temperatures. These results suggest that the Pasir-HyperCoal obtained at higher temperatures contains more, relatively heavy components. Nuclear magnetic resonance measurements showed that the ratio of aromatic carbon increased with increasing extraction temperature, indicating that some modification reactions occurred. (c) 2007 Elsevier Ltd. All rights reserved.