The catalytic pyrolysis of naphtha has been carried out-with 5 mm KVO3-impregnated alpha -Al2O3. The yields of ethylene and propylene exhibit about 10% and 5% higher values compared to the thermal pyrolysis in a vacant tube at the same operation condition. This increase in the olefin yield comes from the thermal effect through the better heat transfer. The amount of coke accumulated on the catalyst during the pyrolysis increases with an increase in the reaction temperature and the axial length of the reactor. The role of KVO3 is to suppress the coke deposition on the catalyst surface. The addition of B2O3 to the KVO3/alpha -Al2O3 system causes a strong interaction between KVO3 and alpha -Al2O3. The results of temperature-programmed reduction and X-ray photoelectron spectroscopy suggest that KVO3 may be reduced to KVO1.5 during the pyrolysis reaction. The weight loss of K and V in the catalyst occurs during the pyrolysis.