A new statistical approach to the electric properties of water at elevated temperatures is proposed. The local permittivity and electrostriction pressure in hydration shells of Sr2+ and Ni2+ ions at ambient conditions, and of Ni2+ ion at elevated temperatures are calculated. The insensitivity of Ni2+ hydration characteristics to the applied pressure is explained by the role played by the much higher local electrostriction pressure. A correlation between the temperatures at which destroyed hydration structures have been observed in recent neutron scattering experiments and the calculated local electrostriction pressures on the one hand, and the melting line of H2O on the other hand, is pointed out. Temperatures at which analogous changes in hydration structure may be expected are predicted for several ions.