The effect of PGPR and added magnesium chloride hexahydrate on properties of W/O (water-in-oil) emulsions was investigated. W/O emulsions were formulated with 60% oil phase containing 0.5%, 1.0% and 2.0% PGPR and 40% aqueous phase containing magnesium salt at various concentrations from 0 to 12.0%. Stability of these W/O emulsions was studied with Turbiscan Lab Expert during 14-day storage. The result indicated that coalescence and sedimentation were the main reasons for destabilization. By increasing the concentrations of PGPR and magnesium chloride, TSI values of W/O emulsions decreased and therefore W/O emulsions became more stable with respect to coalescence. The stabilization mechanism was attributed to the decrease of emulsion droplets and the reduction in interfacial tension. Besides, interfacial viscoelastic measurements between soybean oil and water were conducted. The results indicated that stabilizing effect of PGPR and magnesium salt was not due to the rheological properties of interfacial film. The viscoelastic parameters of interfacial film increased at a lower concentration of magnesium salt (below 2%) while further increasing the concentration of magnesium salt to 6% led to a slight decrease of interfacial viscoelastic parameters. Increasing the concentration of PGPR from 0.5% to 2% led to a reduction in viscoelastic parameters.