Supercritical Carbon dioxide (S-CO₂₎ Brayton cycles have garnered significant attention in the recent past as an alternative source for renewable energy. The present research provides a simplistic, yet robust methodology to appropriately size and design the impeller of a centrifugal compress or for a 12.5 MW_e waste heat recovery S-CO₂ power plant. Two prominent variants of the S-CO₂ cycle are studied and optimized with the aim of maximizing the power output using genetic algorithm. To calculate the geometry from the inlet and exit thermodynamic conditions of the optimized cycle, conservation equations are solved. The impeller is sized and a brief study on condensation in the impeller throat is performed . The effect of multi staging on condensation is investigated. Further, the performance model is coupled with the design scheme to dynamically modify the impeller geometry. Using the developed model, the geometrical parameters of the S-CO₂ impeller are calculated. In addition to the geometry, certain impeller performance parameters are reported and are observed to lie within the permissible limits.