Phthalic Anhydride - Фталевый ангидрид is widely used worldwide for an extremely broad range of applications spanning from the plastics industry to the synthesis of resins, agricultural fungicides and amines. Its production is currently based on the vapor phase oxidation of o-xylene and naphthalene. The development of an alternative production route to the petrochemical one is highly desirable to reduce the pressure on fossil use and effects of oil depletion concerns. This work proposes the process modelling of a bio-based route to phthalic anhydride. Results show how the valorization of all the carbohydrate-rich fractions present in the biomass is crucial to obtain an economically viable process.