Catalytic combustion is considered as one of the most efficient routes for removing volatile organic compounds. In recent years, the catalytic activities of catalysts have usually been evaluated by the values of TOF and T-98. It is difficult, however, to measure the values accurately because the influencing factors are numerous and easy to be overlooked. In this work, the influence of the catalytic test procedure on TOF and T-98 values was investigated. Supported Pd or Pt catalysts were prepared via the incipient wetness impregnation method. The catalytic activities of the same catalyst were very different when evaluated in different catalytic test procedures. Indeed, the catalytic test procedures affected the TOF and T-98 values remarkably. It was found that the different coking behavior in different catalytic test procedures is the major cause. The influences on coke formation in toluene combustion - such as reaction temperature, reaction time, and catalyst type - were investigated.