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The presented study aims to improve the quality of bio-oils by catalytic upgrading of pyrolysis bio-oil from microwave pyrolysis of biomass using transition metal modified activated carbon (AC) catalyst. A central composite experimental design (CCD) was used to optimize the reaction conditions for high quality bio-oil production. The effects of reaction temperature and reaction time on product yields were investigated. GC/MS analysis indicated that the main chemical compounds (including furans, phenols, guaiacols, and ketones/ethers) of bio-oils were in the range of 80-87% of bio-oils for most of the samples. The ketones/ethers were mainly composed of 2-cyclopen-1-one; straight chain ethers were increased up to about 38% of bio-oil; and the phenols increased from 2.5% to about 10% of the bio-oils after upgrading accompanying with the decrease of guaiacols in comparison with raw biomass pyrolysis. Thermogrametric analysis (TGA) was used to analyze the thermal behavior of Douglas fir pyrolysis, and the kinetic parameters were investigated using TGA and compared with catalytic microwave pyrolysis of Douglas fir. The activation energy of catalytic microwave pyrolysis of Douglas fir pyrolysis (~ 3-10kJ/mol) was remarkable lower than that of conventional TGA pyrolysis of Douglas fir (~ 64-118kJ/mol). The reaction mechanism of this process was analyzed.