Despite the higher operating pressure, carbon dioxide has attracted many researchers’ attention because of its higher density, favorable heat transfer characteristics, and environmental friendliness. In order to design components and systems for carbon dioxide, a performance database should be established. As part of the efforts for developing such a performance database, a set of tests were conducted for a fin-and-tube type heat exchanger serving as a gas cooler in the transcritical cycle by using a specially designed test facility. Furthermore, to provide a better understanding of the performance of a carbon dioxide gas cooler, a set of parametric measurements at various inlet air temperatures and velocities, refrigerant mass flow rates, and operating pressures were conducted. The test results of one CO₂ gas cooler are reported in the current paper. In the second phase of the study, fin-and-tube type heat exchangers (as a condenser and an evaporator) and microchannel heat exchangers (as a gas cooler, a condenser, and an evaporator) will be constructed and tested. Then experimental results of those studies will serve as our design database for the CO₂ heat exchangers.