NOVELTY - Process (P1) for treating bio-oil or pyrolysis oil used to produce renewable biofuel, comprises: (a) introducing a feedstream containing bio-oil or pyrolysis oil to a first stage and reducing solids and/or organic reactive molecules within the feedstream in the first stage without deoxygenating the organic reactive molecules in the feedstream; and (b) introducing the feedstream having reduced solids and/or reduced organic reactive molecules to a second stage for producing deoxygenated bio-oil or pyrolysis oil in the second stage.    USE - The process is useful for treating bio-oil or pyrolysis oil used to produce renewable biofuel (claimed), which is used as substituent for fossil fuels.    ADVANTAGE - The process: minimizes fouling within hydrotreaters of solid contaminants and dissolved impurities; and enhances the production of thermally converted oil into liquid hydrocarbons.    DETAILED DESCRIPTION - Process (P1) for treating bio-oil or pyrolysis oil used to produce renewable biofuel, comprises: (a) introducing a feedstream containing bio-oil or pyrolysis oil to a first stage and reducing solids and/or organic reactive molecules within the feedstream in the first stage without deoxygenating the organic reactive molecules in the feedstream; and (b) introducing the feedstream having reduced solids and/or reduced organic reactive molecules to a second stage for producing deoxygenated bio-oil or pyrolysis oil in the second stage, where the second stage is a hydrotreatment stage, and the temperature in the second stage is greater than the temperature in the first stage and the pressure in the first stage is less than or equal to the pressure in the second stage. INDEPENDENT CLAIMS are also included for:    (1) a process (P2) for producing renewable biofuel from bio-oil or pyrolysis oil comprising: (a1) introducing a feedstream containing bio-oil or pyrolysis oil and containing solids and organic reactive materials into a first stage, where the temperature at the entrance is 120-350 degrees F; (b1) reducing the amount of solids and/or reactive species in the bio-oil or pyrolysis oil without deoxygenating the organic reactive molecules at elevated temperature and pressure in the first stage, where the temperature at the entry port of the first stage does not exceed 450 degrees F; (c1) introducing the bio-oil or pyrolysis oil having reduced solids into a second stage, where the second stage is a hydrotreatment stage, and deoxygenating the bio-oil or pyrolysis oil within the second stage, where the temperatures and pressure in the second stage is an amount sufficient to produce a deoxygenated bio-oil or pyrolysis oil; and (d) producing renewable biofuels from the deoxygenated bio-oil or pyrolysis oil; and    (2) a process (P3) for producing renewable biofuels from bio-oil or pyrolysis oil comprising: (a2) reducing solids in the bio-oil or pyrolysis oil in a first stage while minimizing hydrogenation of organic reactive molecules in the bio-oil or pyrolysis oil, where the temperature in the first stage at the port of entry is 120-350 degrees F and the temperature at the exit port of the first stage does not exceed 450?F, the pressure in the first stage is less than 1000 psig, the space velocity within the first stage is 0.2-6, and the amount of organic reactive molecules in the first stage is less than 5%; (b2) deoxygenating the product of step (a2) in a second stage to render deoxygenated bio-oil or pyrolysis oil, where the temperature at the exit port of the second stage is 650-850 degrees F, the pressure in the second stage is 500-2000 psig, and the space velocity within the second stage is less than 2; and (c2) generating renewable biofuels from the deoxygenated product of step (b2).