Waste Heat Recovery (WHR) technologies aim at recovering part of the otherwise wasted heat in the exhaust of a combustion engine and convert it to useful power, resulting in lower fuel consumption and pollutant emissions. Compared to other Waste Heat Recovery (WHR) technologies, Organic Rankine Cycle (ORC) systems are increasingly being regarded for field application as a technology of high potential due to their comparatively higher maturity, relative technological simplicity, lower cost and small back pressure impact on engine performance and fuel consumption. Among the ORC system components, the expander is the most crucial and expensive component in Organic Rankine Cycle (ORC) systems. The present paper present the results of the implementation of an improved Radial Turbine Design (RTD) code which expands on previously published versions and introduces improved blade design features. RTD improves on the stability and preliminary design solution response time, as well as preliminary design accuracy of turbine stage performance, compared to prior methodologies, many of which have been developed and validated for ideal gases and low expansion ratios. The RTD has been coupled with both REFPROP and COOLPROP thermodynamic property software to achieve turbine design solutions for the currently-available libraries of working fluids. © ECOS 2019 - Proceedings of the 32nd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems. All rights reserved.