Abstract: Advanced aircraft engines require designing a transonic turbine stage with large deflection blades. In order to enhance its design aerodynamic load level and to research its design procedure, an existing single turbine stage which was designed as a test model for controlled vortex project has been reconstructed to be a transonic stage with loading coefficient of 2. 4. Aerodynamic design of the stage is characterized by improved parabolic spanwise distribution of work and exit blade angle. The transonic blade profile is a compromise of aerodynamic performance, strength, weight and cooling requirements according to an advanced low solidity design. Two-dimensional cascade testing verifies its favourable performance. Stage testing indicates that the stage efficiency reaches such a level as a turbine of the modernest K. O. Loss system achieves in similar conditions. Measurements of aerodynamic characteristics along the blade height have been shown in good agreement with design parameters.