Two Polish coals are subjected to the reactions of reduction and reductive alkylation in the system potassium/ liquid ammonia. The classical methods of reduction and reductive alkylation of coal are modified by replacing the conventional protonating and alkylating agents by the ones containing deuterium atoms. Reduction is performed with C2H5OD whereas reductive alkylation with CD3I. For the sake of comparison the same reactions are performed with the conventional protonating and alkylating agents without deuterium. It is shown that fragmentation of the coal structure proceeds mainly by cleavage of methylene bridges. The products of reactions of both kinds are subjected to extraction with dichloromethane. The yield of extraction of the modified coals is significantly greater than that of raw coals. Average molecular weights of the extracts are determined, elemental and spectral analyses of the raw materials and products are performed. The effect of the kind of hydrogen isotope in the modifying agents on the results obtained is discussed.