The use of biomass as an alternative fuel to reduce the use of fossil fuels continues to increase, one of which is palm kernel shell (PKS) waste. This study investigated the pyrolysis reactivity of biomass samples (PKS) through thermogravimetric analysis. In addition, the pyrolysis mechanism is approached through the activation energy determined from the model used. This study utilized palm kernel shells as biomass with the addition of iron ore as a catalyst. The TGA test was carried out with variations in the catalyst composition (0, 10, and 15% of total mass) and heating rates (5, 10, and 15 °C/min) of the pyrolysis process. The kinetic parameter, E, was estimated using the independent model method, namely FWO (Flynn Wall Ozawa) and KAS (Kissinger Akahira Sunose). The study showed that the concentration effect on the conversion rate was almost the same for all concentrations in heating rate of 10 °C/men. The heating rate of 15 °C/min provided the highest conversion rate compared to the other two heating rates. Furthermore, the activation energy values fluctuated in the kinetic analysis using the FWO and KAS methods. Besides, the best fit is obtained from the conversion of 0.2-04 and 0.8-0.9.