In this work, rice husk, an agricultural waste in Korea, was pyrolyzed under different reaction conditions (temperature, flow rate, feed rate, and fluidizing medium) in a fluidized bed with the influence of reaction conditions upon characteristics of the bio-oil studied. The optimal pyrolysis temperature for bio-oil production was found to be between 400 and 450°C. Higher flow rates and feeding rates were more effective for its production. The use of the product gas as the fluidizing medium led to the highest bio-oil yield. With the exception of temperature, no single operation variable largely affected the physicochemical properties of the bio-oil.