The growing need for mass travel in an increasingly interconnected world and the urgent awareness of climate change is stimulating the search for innovative solutions for high-speed aviation. This thesis aims to define a conceptual design methodology for the development of a sustainable supersonic commercial aircraft, cruising at Mach 2 and powered by biofuel. The approach presented allows a high-level estimation of aircraft performance and geometric characteristics, the determination of a design point capable of meeting precise operational and environmental requirements during mission accomplishment, and the evaluation of the features of new biological propellants. This study, therefore, offers a guiding tool for engineers and stakeholders in the aeronautical sector, contributing to the realisation of a future in which supersonic transport is not only synonymous with-high speed, but also with environmental sustainability..