The aim of the work was to investigate the mechanism of cracking of n-heptane in the presence of a medium-pore finely crystalline catalyst based on zeolite ZSM-5 and the development of a kinetic model of the mechanism of the thermic and catalytic reaction. The catalyst based on zeolite ZSM-5 has high catalytic activity for the catalytic cracking of n-heptane, high stability, and long life time. The kinetic model includes 12 chemical substances and 11 reactions. The values predicted by the model were in good agreement with the experimental data, and the average relative error in the main products was not greater that 10%. The model showed good agreement between the calculated yields of the final product and the experimental data for the catalytic cracking of n-heptane.