A cylindrical bubbling fluidized bed reactor having 2 kg/h pyrolysis capacity was developed and using this reactor fast pyrolysis of lignocellulosic biomass was carried out to obtain biocrude oil. In the fast pyrolysis system, a commonly used spiral quenching heat exchanger with electrostatic precipitator was applied to condense volatile gases issuing from the reactor. In the present study, various experimental parameters were considered mainly to elucidate the effect of pyrolysis reaction conditions on the yield of final product such as biocrude oil, char and non-condensable gas. Hence, biomass feeding rate, biomass particle size, nitrogen flow rate, heating temperature and cooling temperature were selected for the experimental reaction conditions. As increasing the biomass feeding rate, the biocrude oil yield is increased from 54.6% to 57.8% and with increasing biomass particle size, decreased from 56.9% to 51.3%. With increasing the nitrogen flow rate, the biocrude oil yield is firstly increased from 53.9% to 54.8% and then decreased to 50.6% and the maximum biocrude oil yield is 57.0% for 500 degrees C. As the cooling temperature is increased, the biocrude oil yield is decreased from 55.7% to 47.9%. From the results, it was found that the bubbling condition, vapor residence time and heat transfer played an important role on the thermal conversion of biomass and its final product. (C) 2011 Elsevier Ltd. All rights reserved.