Pyrolysis process of hazelnut shell was carried out in a stainless steel tube with height 95.1 mm, I.D. 17.0 mm and O.D. 19.0 mm by heat in the absence of oxygen, which results in the production of charcoal, liquid and gaseous products. The yields of gaseous products increase with increasing pyrolysis temperature for all runs. In general, the yields of liquid products increase with increasing pyrolysis temperature from 650 to 700 K, then it decreases with the temperature. The highest liquid yield is 32.1% of the sample with +0.150 mm particle size. Increase of temperature is sharply in all initial 130 s period. The average rate of temperature is 3 K/s in this period. In a 60 s to 90 s period, the average rate of temperature is higher than 6 K/s for the samples with -0.063 mm, +0.060 mm, and +0.150 mm. The average rate Of temperature is slow and regular from 150 s to 570 s.