The regularities of destructive and polycondensation processes in lignites of the Soma coal field, Turkey, were investigated by the methods of EPR, IR spectroscopy, derivatography and chromatography. It was shown that on lignite irradiation by gamma-rays the character of the processes changes, depending on the absorbed dose and temperature. At room temperature and doses up to 200 kGy irradiation leads to the accumulation of radiation defects, which stimulate destructive reactions. At higher doses, due to the recombination of radiation defects, there is radiation lacing of the organic mass of coals. On the conjugate action of heat and irradiation on coals, destruction processes predominate. The mechanism of radiation effect upon coals is explained within the scope of the conception of self-associated multimer structure of coals.