Firstly, the operating conditions were screened for biomass pyrolysis in a fixed bed with respect to higher oil yield. A temperature of 600 °C with an N₂ flow of 80 ml/min exhibited the highest bio-oil yield. Then, the catalytic pyrolysis of biomass with various catalysts (Al₂O₃, CaO, MgO, CuO, Fe₂O₃, NiO, ZnO, ZrO₂, TiO₂, HZSM-5 and MCM-41) was studied to identify the selective deoxygenation method with respect to improve bio-oil quality with smaller drop in bio-oil yield. With the addition of CaO, the oxygen was mainly removed in the form of CO₂, while, in other cases, more oxygen was removed in the form of H₂O. Furthermore, more decarboxylation or less dehydration is better for the balance between yield and deoxygenation amount, and the preferred decarboxylation would lead to a higher pH and lower moisture content of bio-oil.