Radical formation in Victorian brown coal has been investigated by using in situ high temperature ESR apparatus which can detect relatively stable π and σ radicals during heat treatment. In this work, it was found that increase in the radical concentration as temperature rising was suppressed by transferable hydrogen (TH) in recycle solvent at around 400℃. And the result of autoclave test suggested that pretreatment of coal at around 350℃ with hydrogen-donating solvent was effective to inhibit retrogressive reactions. It is discussed about the effect of radical stabilization by TH and the influence on structural properties of the products at initial stage.
