In this paper, a method for improving the efficiency of the cascade mechanical compression ejector cooling cycle is described. The considered cooling cycle is the combination of the electrically driven carbon dioxide (CO2) subcritical mechanical compression cooling cycle as a bottoming cycle, and the heat driven ejector cooling cycle as a topping cycle. This cooling cycle is proposed to use superheated CO2 vapor to preheat the working fluid supplied to the vapor generator, thus improving the whole system's efficiency. This paper provides thermodynamic analysis results for the cascade cooling system in a wide range of evaporating temperatures. Refrigerants R245ca, R600, and R601b were investigated as the working fluids for the ejector cooling cycle, and the results show that the proposed cooling cycle is the most effective at low evaporating temperatures. (C) 2018 Elsevier Ltd. All rights reserved.