In this study, water hyacinth was converted into highly flammable bio-oil via two-step catalytic pyrolysis. The upgradation of bio-oil was based on the pretreatment of biomass, second-step pyrolysis and use of clinkered material as a catalyst. This three-prong approach was found effective for improving the nature and yield of the oil by lowering the water and oxygen content in the product. The yield of oil was investigated as a function of pyrolysis temperature and weight of the catalyst in addition to pretreatment of biomass. Optimum time for the reaction was also investigated for all three types of biomass. In the preliminary pyrolysis, each of the sample was pyrolyzed into an aqueous liquid, gas, and solid residue fractions. The liquid fraction of each of the sample was separated into combustible and non-combustible liquids in addition to residue using fractional distillation. The residue of the fractional distillation for each of the fresh, putrefied, and microbe-treated biomass was re-pyrolyzed and the gas produced during 1st and 2nd steps of the pyrolysis was analyzed using chemical analysis. The upgraded oils were analyzed for their composition with GC-MS technique. The oil products of the tested samples were significantly differing from each other in terms of nature and number of the compounds. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 1836�1844, 2018. © 2017 American Institute of Chemical Engineers