The catalysis of carbon black was investigated for the production of hydrogen by the catalytic decomposition of propane-butane mixture gas in this study. The thermal and the catalytic decompositions of hydrocarbons were performed at the temperature range of 500 - $1100^{circ}C$, respectively. The conversions of hydrocarbons and the mole traction of hydrogen increased with increasing the reaction temperature and the conversion of hydrocarbons in the catalytic decomposition process was approximately liked with that obtained by the thermal decomposition. However, the mole traction of hydrogen produced in the catalytic decomposition process was higher than that obtained from the thermal decomposition. Therefore, it was concluded that the catalysis for the decomposition of hydrocarbons is occurred over carbon black used as catalyst. The mole traction of hydrogen produced by the catalytic decomposition of hydrocarbons also increased with increasing the mole ratio of $C_3H_8/C_4H_{10}$ in propane and butane mixture gas at $700^{circ}C$. Therefore, it was concluded that the catalytic decomposition of the high propane mixture gas is more effectively for the production of hydrogen.