Carbon dioxide (CO2) is one of the natural refrigerants which can be used as working fluid in various refrigeration applications along with the ammonia and hydrocarbons due to its eco-friendliness, higher volumetric capacity, good heat transfer properties, etc. The present article consists of two parts: A detailed comparative study of CO2-based transcritical refrigeration systems with conventional refrigerants-based systems in terms of both thermodynamic and heat transfer performances, and review of both theoretical and experimental researches on transcritical CO2 vapor compression cycle for various refrigeration applications including commercial product status. Suitability of the CO2 system in specific refrigeration application is also discussed.