Fast pyrolysis of biomass is the most promising technology of converting solid biomass to liquidrnbio-oil as a renewable substitution of fossil resources in fuel and chemical feed stocks applications.rnEthiopia with abundant biomass resources especially from coffee processing industry has thernpotential to provide an ideal platform for the development of this thermal conversion technology.rnThis thesis was aimed of developing a 145 mm reactor diameter pilot scale fast pyrolysis systemrnwith coffee husk as the main feedstock.rnFor detail analysis of the fast pyrolysis system a two-stage fluidized bed reactor was designedrnbased on the fluidization technology with silica sand as the heat carrier to achieve rapid heatrntransfer required for the reaction. The amount of silica sand required was determined from thernhydrodynamics and heat transfer performances. The assembly of the system consists of five mainrnsections. These are the feed hopper, reactor subsystems (reaction chamber, gas-preheating chamber,rnplenum, and gas distributor plate), cyclone separator and condensation system. Smooth process andrnsubstantial bio-oil yields could be achieved for the experiments carried out with the reactionrntemperature within 300 to500 . But due to lack of appropriate fluidizing medium (lack ofrncontinuous gas supply compressor) the maximum gas temperature in the reaction chamber achievedrnwas only 100 .rnKey Words: Biomass, Fast pyrolysis, Bio-oil