Aerospace vehicles with fixed geometry are designed to operate at a predetermined flight condition. Variation of the aerodynamic environment, such as during acceleration, climbing, or turning, from the design condition reduces the efficiency of the vehicle. It would be advantageous to be able to adapt the vehicle geometry to maintain efficient flight over a range of aerodynamic conditions. Morphing sandwich structures offer sufficient strength and stiffness to serve as aerodynamic surfaces, while providing the shape-changing authority to attain a range of surface profiles without additional joints or seals. As a demonstration of the morphing concept in a supersonic environment, this paper describes the construction and testing of a morphing nozzle for a supersonic wind tunnel, which has been designed to operate isentropically over a Mach range from 2.5 to 3.8. The nozzle has been installed and operated in this Mach number range and the experimental results are presented.