Three various coal tar pitches and mixt. of coke and NaSCN were heat treated under Ar or N(2) up to 1000 degrees C and 1100 degrees C, resp., at varying heating intensity to det. the mass loss rates. The thermogravimetric curves were analyzed to disclose the reaction mechanisms. In the case of pitches, formation of mesophase, coking, formation of fixed C and evolution of H(2) were obsd. In the case of coke-NaSCN mixt., dehydratation of NaSCN, its decompn. to Na(2)S, CS(2), C(2)N(2), C and N(2), and decrepitation of solid residues were obsd. The temp. relationships of the relative reaction rates were detd.