By using high temperature ESR and TG-MS, radical formation in Victorian brown coal by thermal decomposition was investigated and structural change, of coal at initial stage is discussed in this report. It was found that there are two steps of increase in radical concentration at the temperature of 200 to 350℃ and higher than 350℃. From the result of TG-MS, they were suggested the possibility of relation to decomposition of oxygen containing functional groups and cleavage of C-C bonds respectively. When coal was heated with Dihydroanthracene, radical concentration was reduced in the region of 200 to 350℃ than the case of 1-Methylnaphthalene. Moreover, ordinary ESR spectra of coal pretreated above 350℃ showed that radical concentration was lowered by tetralin added solvent. It suggests that transferable hydrogen in solvent suppressed the formation of aromatic π radicals in pretreated coal
