This document summarizes the design optimization and analysis of an impeller for a centrifugal compressor. It begins with background on centrifugal compressors and their applications. The aim is then stated as developing a methodology to design a centrifugal compressor impeller accounting for real fluid effects. A computer program is developed based on jet-wake theory to estimate impeller dimensions. The methodology is validated by comparing results to an existing impeller design, showing encouraging accuracy. The method is then applied to design an impeller for an air conditioning system using R-12 as the refrigerant at 18,000 rpm. Key design parameters are examined at varying speeds to select optimal values.