The gas cooler pressure is one of the most important design parameter for energy and exergy efficiencies of a transcritical CO2 (R744) cooling system. In this study, the optimum gas cooler pressure is obtained as a function of evaporation temperature of CO, and outlet temperature of CO2 following the gas cooler. The presented correlation is valid for -25 degrees C < T-b < 0 degrees C and 30 degrees C < T-gs,T-c < 55 degrees C. The obtained correlation is presented with a three dimensional graphic for these limits. The evaporation temperature interval is wider than the recent literature works, so this is the importance of this correlation. However a comparison is presented between correlations presented a literature work and presented with this study.