While commercial aviation continues to grow, achieving climate goals set for this industry becomes more important. Since no major breakthroughs have been accomplished in the field of conventional kerosene-powered aircraft lately, new concepts and fuels are required. The use of liquid hydrogen as an aircraft propellant is currently considered to be one of the possibilities to accomplish a large reduction in the climate impact of aviation. However, the large volumes required for liquid hydrogen storage impose a challenge in aircraft implementation. The blended-wing-body concept is identified as a potentially suitable platform for integrating these large tanks due to its relatively large internal volume compared to its wetted area. The objective of this research is to attain the optimum aerodynamic shape of a liquid-hydrogen-powered, 150-passenger, medium-range, blended-wing-body. This is done by performing a constrained shape optimization for maximum aerodynamic efficiency. The concept specifications and sizes follow from a kerosene-powered reference aircraft. The aircraft geometry is defined for an inside-out driven design where the cabin and tank are integrated in tandem into the centerbody. The ParaPy platform is used to couple the parameterized geometry to a meshing suite and the aerodynamic analysis methods. The geometry is transformed into an unstructured mesh by using the Salome platform. The aerodynamic analysis of the wave and induced drag consists of using the Euler equations and is computed within the Stanford University Unstructured code. Empirical strip methods provide the viscous drag estimate. Two optimization approaches are employed in this study, both making use of an evolutionary algorithm. Optimizations take place based upon a baseline design and include both geometric and aerodynamic constraints. The dual step approach consists of a 13-variable planform optimization followed by a 49-variable optimization of six two-dimensional profiles that are located along the span. The single step approach includes 50 variables of both the planform and wing profiles. The optimization computations take place at a single cruise condition where the Mach number is 0.78, the lift coefficient is equal to 0.2 and the atmospheric conditions follow from a cruise altitude of 11,000 meters. The dual step and single step optimizations yielded an 8.7% and 7.5% performance increase compared to a baseline. The resulting lift-to-drag ratios of the optimized designs are 20.5 (dual step) and 20.3 (single step). Both optimizations resulted in different shapes. The single step optimization features an aft-positioned outer wing, which has a leading-edge sweep angle of 47-degrees. The dual step optimized design features a more forward-positioned wing with 51-degree leading-edge sweep. Both optimized designs do not display shockwaves and the lift distribution tends to an elliptical shape. The long center chord length of around 37 meters, results in a relatively low centerbody lift coefficient, while a cross-sectional area distribution close to a Sears-Haack body is attained.