Woody biomass can be transformed into a liquid product through pyrolysis. Other products from this process are a solid biomass residue called char and non-condensable gases mainly CO, CO2 and light hydrocarbons. The liquid product, which is highly oxygenated, can be upgraded by removing oxygen. Application of zeolites in the upgrading removes the oxygen as water at low temperatures and as CO and CO2 at higher temperatures (1, 2, 3). A dual-fluidized bed pyrolysis reactor has been developed at the Laboratory of Industrial Chemistry and Reaction Engineering at åbo Akademi University. The reactor has two fluidized beds on top of each other. In the lower bed quartz sand is used as bed material in the thermal pyrolysis of biomass. The bed material of the upper can be different types of catalysts used to upgrade the pyrolysis vapours from the first reactor. The heating of the reactors is performed in a furnace. Zeolite Beta and ZSM-5 have been tested in the catalytic upgrading of pine wood biomass pyrolysis vapours at 450°C. The obtained bio oil has been analyzed by Karl Fischer titration, GC-MS, and GC-FID to investigate the influence of the different zeolites. The yield of the product phases is given in Table I.