The solubility and the physicochemical properties (density, viscosity) in the Na-Zn- Cl-H2O), (Na + Zn + H2PO2 + H2O), (Na + Cl + H2PO2 + H2O), and (Zn + Cl + H2PO2 + H2O) ternaries, and in Na+, Zn2+/Cl-, (H2PO2)(-)//H2O reciprocal quaternary systems at T = 273.15 K were investigated by using the isothermal method. The diagrams of ternary salts systems, (NaCl + ZnCl2 + H2O), (NaCl + NaH2PO2 + H2O), (NaH2PO2 + Zn(H2PO2)(2) + H2O), (ZnCl2 + Zn(H2PO2)(2) + H2O), are plotted in figures 1-4. However, whole ions of reciprocal quaternary salt systems are plotted in figure 5. Additionally, the density and viscosity values of ternary systems vs. their corresponding composition values in weight per cent are plotted in figures 6-10. At the (i) (ZnCl2 + Zn(H2PO2)(2) + H2O), (ii) (NaCl + ZnCl2 + H2O), (iii) (NaCl + NaH2PO2 + H2O), (iv) (NaH2PO2 + Zn(H2PO2)(2) + H2O) ternary systems the solid phase compositions have been determined as: (i) Zn(H2PO2)(2) center dot H2O, Zn(H2PO2)(2), ZnCl2 center dot 2H(2)O, (ii) NaCl, 2NaCl center dot ZnCl2 center dot 2H(2)O, and ZnCl2 center dot 2H(2)O, (iii) NaCl and NaH2PO2 center dot H2O, (iv) Zn(H2PO2)(2) center dot H2O and NaH2PO2 center dot H2O, respectively. On the other hand reciprocal quaternary system was observed as: ZnCl2 center dot 2H(2)O, 2NaCl center dot ZnCl2 center dot 2H(2)O, Zn(H2PO2)(2) center dot H2O, NaH2PO(2) center dot H2O, NaCl. According to results, the least soluble salt was Zn(H2PO2)(2). The crystallization field of this salt, being the largest in comparison with those of other salts, occupied 70% of the general crystallization field. (C) 2014 Elsevier Ltd. All rights reserved.