Catalytic pyrolysis of pine biomass was carried out in a fluidized bed reactor at 450 degrees C. The acidic catalysts used as bed material in the reactor were B-zeolites with varying silica to alumina ratio, thus having different acid strengths. Quartz sand was used as bed material in the non-catalytic experiment. The yield of the different product phases was clearly influenced by the zeolites acidity. The chemical composition of the bio-oil was dependent on the catalyst. Zeolites with stronger acidity formed less organic oil, and respectively more water and polyaromatic hydrocarbons than less acidic zeolites.