This study presents a comparative analysis of thermodynamic performance of cascade refrigeration systems (CRSs) for refrigerant couples R41/R404A and R23/R404A to discover whether R41 is a suitable substitute for R23. The discharge temperature, input power of the compressor, coefficient of performance (COP), exergy loss (X) and exergy efficiency (eta) are chosen as the objective functions. The operating parameters considered in this paper include condensing temperature, evaporating temperature, superheating temperature and subcooling temperature in both high-temperature cycle (HTC) and low-temperature cycle (LTC). The results indicate that an optimum condenser temperature exists for LTC (T-4opt) at which COP acquires maximum value. Under the same operation condition, the input power of R41/R404A CRS is lower than that of R23/R404A CRS, and COPopt is higher than that of R23/R404A CRS. The maximum exergy efficiency of R41/12404A and R23/R404A CRSs are 44.38% and 42.98% respectively. The theoretical analysis indicates that R41 /R404A is a more potential refrigerant couple than R23/R404A in CRS. (C) 2016 Elsevier Ltd. All rights reserved.