The gasification reaction rates by in of various compositions in the temperature range of were measured for foundry coke and anthracite lump. The data for the rates was analyzed with Langmuir-Hinshelwood rate equations for the gasification of carbonaceous specimens. The values of the apparent activation energies of the reactions obtained from these data were ranged to be 47-99 and 73-128Kcal/mol respectively for foundry coke and for anthracite lump. The major contribution to decrease in tensile strength was shown to be attributable to the enlarging of the macropores in the coke and that of crack in the anthracite lump. Under the same experiment of the gasification of foundry coke, the rate of form coke was increasing as the addition of increases.