Avoiding crystallization in the exchangers is the main challenge in the operation of a Run-Around Membrane Energy Exchanger (RAMEE) system. In the present study, crystallization risk of two binary salt solutions (LiCl-Water and MgCl₂-Water) was investigated in the RAMEE system as a novel air-to-air energy recovery device. The effect of different climatic conditions and design parameters of the system on the risk of crystallization of these two salt solutions was also studied in detail. It is shown that in very dry outdoor conditions the MgCl₂-Water solution may crystallize in the RAMEE system while the LiCl-Water solution operates without crystallization issues in almost all climatic conditions. A MgCl₂ solution, as a cost effective alternative for a LiCl solution, may still be used in normal operating humidities.