Electromotive force valuated on NaCl-Ca(NO3)2-H2O system with a cell consisting of Na+ion-selective electrode and Ag/AgCl electrode. Pitzer equations were applied for analysis of data. Electrolytic aqueous samples collected from Musi River at Nagole, Hasmathpet, Lake Peripheral and Musi River, Pilaipally, Ghatkesar (Mandal) of Hyderabad were subjected estimation of activity coefficients of using ion-selective electrodes. Aqueous electrolyte fluids thermodynamic properties i.e., activity coefficients, TDS, SAR and SAR(td) their play an important role in understanding the behaviour of water from different sources which are useful in Oceanography, Geo-chemistry, Petroleum drilling, different sources of waters such as Polluted water, Industrial waste water and also Biological fluids.