Nowadays raw empty corn cobs have been used as substitute fuel in conventional boilers in corn mills, in which the thermal efficiency is low because of its poor fuel properties. The fuel property of empty cobs can be improved by torrefaction process. This study focuses on the in-depth study of the gasification process using raw empty cobs and torrefied empty cobs as solid fuel. The gasification process was carried out in a batch-type laboratory scale downdraft gasifier at the air flow rate of 250 liters per minute for raw empty cobs, and 250, 300, and 350 liters per minute for torrefied empty cobs. The temperature distribution in each reaction zone, the producer gas composition, the heating value of the producer gas, and finally the cold gas efficiency obtained from the gasification of the raw empty cobs and terrified empty cobs were compared. The experimental results showed that the gasification of the torrefied empty cobs can provide better gasification behavior than raw empty cobs. The temperature in each reaction zone was higher for torrefied empty cobs, which ranged from 846.5°C to1,291.6°C in the combustion zone, and from 720.1°C to 838.8°C in the reduction zone, whereas the temperature in the combustion zone and reduction zone in the case of using raw empty cobs varied from 715.5°C to 909.7°C and 709.9°C to 814.5°C. Furthermore, the temperature distribution along the height of the gasifier was more stable for the torrefied empty cobs. The producer gas obtained from the gasification of the raw empty cobs contained more CO (18.20-27.79 %-vol.), H2 (3.63-9.37 %-vol.) and CH4 (0.17-0.33 %-vol.), but less CO2, O2, and N2 than that obtained from the terrified empty cobs, which contained 5.72 %-vol. CO, 0.97 %-vol. H2 and 0.03 %-vol. CH4. The higher CO, H2, and CH4 led to a higher heating value for the producer gas and cold gas efficiency for the torrefied empty cobs. The producer gas heating value increased from 0.835 MJ/Nm3 for the raw empty cobs to 2.84-4.25 MJ/Nm3 for the torrefied empty cobs, and the cold gas efficiency increased from 31% for the raw empty cobs to 55-87% for the torrefied empty cobs.