Mankind always needed cooling technology as well as heating technology for maintaining daily life. For this reason, it is an indispensable requirement for mankind to live in ease and comfort in an air conditioned and cooled place besides heated one. This situation, day by day increased work done on development of cooling technology. In this study, short history of refrigerants used on refrigeration or heating systems, definitions and physical and thermodynamic characteristics of refrigerants were considered. In addition, the effects of these refrigerants on global warming and ozone layer, alternative refrigerants and considerations at the selection of the refrigerants were expressed. The effects of refrigerants on global warming and environmental pollution, rates of ozone layer deformation, flammable, toxic characteristic and vaporization and critical temperatures of refrigerants were considered and with the lighting of literature cited, alternatively refrigerants may be suggested were determined. Separately the effects of using of refrigerants mixture as alternative refrigerants instead of pure refrigerants on the performance of refrigerants systems were considered with the lighting of Lorenz cycle and superiority of the using of refrigeration’s mixtures was covered.