<p>The ammonia/CO₂ combination is now considered the most optimum selection for cascade refrigeration applications, specifically at temperatures up to 216.58&#xa0;K. Nevertheless, to get temperatures lower 216.58&#xa0;K, it is important to employ a blend of CO₂ alongside other refrigerants. Aim of this study was to examine the practicality of using CO₂ mixtures in applications that need temperatures lower than the triple point. CO₂ composition varies between a mole percentage of 0.1 and 0.8, alongside the inclusion of R23, R32, R41, and R125. Properties of tested mixtures were determined using Ref Prop 7.0 along with used in the EES software. Ammonia is employed as a refrigerant in circuits that operate at high temperatures. The impact of various operating parameters such as mole fraction, intermediate temperature, sub-cooling and super-heating of the refrigerant has been examined. The combination of CO₂ and R125, with a mole fraction ratio of 0.3/0.7, outperforms all other mixes in terms of providing the highest COP values. When comparing blends with identical mole fraction ratios, the CO₂/R125 mixture outperforms other blends. At a mole fraction ratio of 0.8/0.2, mixtures R744/R125, R744/R41, and R744/R32 have almost comparable values of the Coefficient of Performance (COP), with the R744/R32 blend having the lowest COP. The coefficient of performance is increased by superheating and cooling by around 1% at the optimal temperature. Thus, R744 blends are an optimal selection in case of low-temperature circuit of cascade systems that function at temperatures in proximity to 200&#xa0;K.</p>