Ejection refrigeration cycles are driven by thermal energy. Application of low-grade heat as a motive source, e.g. district heating system requires sufficient mass flow rate of the heating water or large change of temperature of the water in order to provide required heat flux. The latter is more economically advantageous. In some cases, however, either requirements can not be fulfilled. One of the reason is isothermal evaporation of refrigerant in vapour generator. Because of this the refrigerant with temperature glide is highly recommended. The paper deals with thermodynamic analysis of low GWP refrigerant mixtures applied for ejection cycle. The results show that depending on the type and proportion of mixed refrigerants the temperature of the heating medium change from 5 to 25 K and more. As an effect the COP of the system vary between 5 to 25%.