The NO reduction characteristics of a vanadium supported activated carbon catalyst have been examined without addition of reducing agent (i.e., ammonia, NH 3 ). The catalyst was prepared from commercial coconut activated carbon that was impregnated with 2.8wt.% vanadium. The NO reduction reactions were conducted under conditions with 3% O 2 and without O 2 in a fixed bed reactor. In the condition with O 2 , 84% NO conversion resulted at 360°C, though the catalyst began to burnout at a temperature higher than 300°C and with large quantities of CO and CO 2 being emitted. In the condition without O 2 , the burnout of the catalyst was insignificant and resulted in small amounts of CO and CO 2 . The NO conversion increased gradually with the reaction temperature reaching 78% at 450°C. SEM photographs and BET measurements are useful tools for understanding the burnout phenomena with the catalyst. The burnout in the condition with O 2 resulted in the catalyst rapidly losing its activity. However, in the condition without O 2 , the catalyst gradually lost its activity and finally approached a steady state. Moreover, the modified mechanism scheme of the NO reduction reactions without NH 3 and with the catalyst is described and the global rate equation for the reaction without O 2 is obtained.