Unlike previous approaches, this study aims to increase the cycle efficiency of an S-CO\({}_{2}\) Brayton cycle by improving the aerodynamic performance of an S-CO\({}_{2}\) centrifugal compressor. Figure 2 shows classical configuration of an S-CO\({}_{2}\) Brayton cycle. Compared to the conventional Brayton cycles, an S-CO\({}_{2}\) Brayton cycle feature low expansion ratio and high regeneration. Figure 3 shows the sensitivity analysis of S-CO\({}_{2}\) Brayton cycles relative to CIT and compressor isentropic efficiency variations. It can be found that the cycle efficiency becomes more and more sensitive to the compressor efficiency as CIT increases. An S-CO\({}_{2}\) Brayton cycle operating near the critical point is relatively insensitive to the compressor efficiency on the cycle performance because of its small compression work. However, as the cycle moves further away from the critical point and consequently requires more compression work, higher compressor efficiency becomes very important to the system performance. This supports the importance of research for improving the compressor performance in an S-CO\({}_{2}\) Brayton cycle with dry cooling. When designing turbomachinery, complex analyses to evaluate mechanical feasibility have to be performed, which finally leads to fixing the design parameters. However, the design process often involves fixing design parameters from experience of each designer to close the mathematical relations of design parameters and performance. Various institutions have tried to manufacture and test S-CO\({}_{2}\) compressors in their facilities by collaborating with turbomachinery vendors. Sandia National Laboratory and Barber-Nichols Inc. in the U.S. and KAIST, Korea Atomic Energy Research Institute and Jinsol Turbo Machinery in Korea are examples of such collaboration [7; 8; 9]. However, these experimental studies have mostly focused on applying existing accumulated air compressor technologies to the S-CO\({}_{2}\) compressor since an S-CO\({}_{2}\) Brayton cycle is not yet mature power generation technology. More specifically, due to issues with bearing and seal, the amount of data is limited to investigate how different the S-CO\({}_{2}\) compressor can be in terms of aerodynamic characteristics from the air compressor [10; 11; 12]. The most important process in the aerodynamic design of a centrifugal compressor is to select the backsweep angle at impeller exit because it can improve the isentropic efficiency, extend stable operating range and raise the degree of reaction. Traditionally, the centrifugal compressor has pursued higher backsweep angle, however, due to the limitation on the materials to withstand high levels of tip speed and temperature the angle is restricted to about \(-50^{\circ}\)[13; 14; 15; 16]. For designing the S-CO\({}_{2}\) centrifugal compressor, thermodynamic properties variation near the critical point of CO\({}_{2}\) has to be considered unlike from the air centrifugal compressor. Thus, it is natural to investigate how these characteristics may affect the optimum backsweep angle. The selection of the optimum angle will depend on its operating conditions such as the static temperature and the static pressure at the compressor inlet. Therefore, this paper will cover the effect of backsweep angle changes on the S-CO\({}_{2}\) centrifugal compressor performance using a 1D mean stream-line method.