In a lab scale tube furnace, mixtures of coal and biomass were co-pyrolyzed under nitrogen atmosphere condition to become chars. Then these chars were co-gasified with CO2 under isothermal conditions. CO concentration was measured by a real time gas analyser with NDIR (Non-dispersive infrared) CO and CO2 sensor. The furnace temperature was varied between 900-1100°C. The Volume Reaction Model (VRM), Shrinking Core Model (SCM) and Random Pore Model (RPM) were used to interpret the experiment data. The activation energy (Ea) and frequency factor (A) of coal and biomass char-CO2 reaction were determined using the Arrhenius equation. As a result, the reactivity on co-gasification of blended chars was improved than single coal char because of catalysis of alkaline minerals which were included in biomass char.