The mixed aqueous electrolyte system containing the chlorides of lithium, potassium, rubidium, and magnesium has been investigated using the method of isothermal evaporation at 323 K. The space diagram, the planar projection diagram and the water content diagram have been constructed based on the janecke method. There are six invariant points, eighteen univariant curves, and eight crystallization fields corresponding to single salts lithium chloride monohydrate (LiCl center dot H2O), bischofite (MgCl2 center dot 6H(2)O), a solid solution of potassium and rubidium chloride [(K,Rb)Cl], and carnallite type double salts LiCl center dot MgCl2 center dot 7H(2)O. KCl center dot MgCl2 center dot 6H(2)O, and RbCl center dot MgCl2 center dot 6H(2)O in the space diagram. With a view to the crystallization zones, the crystallization zone of salt [(K,Rb)Cl] occupies the largest part, meaning [(K,Rb) Cl] can be more easily separated from solution than the other coexisting salts in this system at 323 K. (C) 2014 Published by Elsevier B.V.