This paper deals with the preparation of magnesium chloride hydrate from a mixed salt solution containing, besides MgCl 2 , substantial quantities of undesired substances such as alkali metal chlorides and magnesium sulphate. Magnesium chloride extraction was done using dioxan. In particular, it was found that this salt precipitate as the ternary compound MgCl 2 ·6H 2 O·C 4 H 8 O 2 . Reaction equilibrium is reached after 40min. It was shown that solid phase MgCl 2 ·6H 2 O·C 4 H 8 O 2 conversion into MgCl 2 ·6H 2 O is feasible by a drying carried out at constant temperature chosen in the range (70–110°C). Physico-chemical properties of the final product are determined using XRD, complexometry, potentiometry, gravimetry and FAAS. Prepared MgCl 2 ·6H 2 O purity is upper than 99%. Its X-ray diffractogram is impurity free.