The rheological and thermal properties of sodium form gellan gum solutions with and without sodium chloride, potassium chloride, calcium chloride and magnesium chloride were studied by dynamic viscoelastic measurement and differential scanning calorimetry, Temperature dependence of the loss modulus for gellan gum solutions of lower concentrations without salt showed a one step-like change at a certain temperature, however that for concentrated gellan gum solutions (>2.0%) showed two step-like changes. The higher temperature process T-hc may be attributed to the helix-coil transition and found in between the exothermic and endothermic peak temperatures T-s and T-m observed in cooling and heating DSC curves, while the lower temperature process T-sg may be attributed to the sol-gel transition. Temperature dependence for gellan gum solutions of higher concentrations (>3.2%) showed a large hysteresis, moreover, the temperature at which the loss shear modulus G " showed the second step decrease shifted to higher temperatures with increasing concentration of gellan gum. The cooling or heating DSC curves for gellan gum solutions of lower concentrations showed a single exothermic or endothermic peak, and both exothermic peak temperature T-m and endothermic peak temperature T-m shifted to higher temperatures, and both exothermic and endothermic enthalpies increased with increasing concentration of gellan gum. However, for a gellan gum solution of a concentration higher than 3.2%, the endothermic peak in the heating DSC curve split into two peaks, while the cooling curve showed only one endothermic peak. The lower temperature endothermic peak in the heating DSC curve corresponds with the first step decrease of G " in the heating process of rheological measurement, and the higher temperature endothermic peak corresponds with the second step decrease of G ". The viscoelastic change of gellan gum solutions was more remarkable by the addition of K+ than Na+, and by Ca2+ than by Mg2+. The viscoelastic behavior of gellan gum solutions was influenced much more strongly by divalent cations than by monovalent cations. DSC cooling curves of gellan gum solutions showed a single exothermic peak shifting to progressively higher temperatures with increasing concentration of monovalent cations. At low concentration of monovalent cations, the DSC heating curves showed a single endothermic peak, however, with more progressive addition of salt, the endothermic peak gradually developed bimodal character and eventually split into multiple peaks. With increasing concentration of divalent cations, the exothermic and endothermic enthalpies estimated for a main peak increased up to a certain concentration and then decreased. Moreover, the endothermic peaks in the presence of sufficient salts were too broad to be resolved from the baseline, and many other peaks were observed at higher temperatures. Gellan gum solutions with sufficient divalent cations form firm gels on cooling to below the setting temperature, and then it was difficult to remelt them, which was quite different from the behavior of thermoreversible gels formed in the presence of monovalent cations.