In first part of this work, a new ion selective PVC membrane electrode based on bis(benzoylacetone) propylenediimine as an ionophore is developed as a sensor for the determination of mercury(II) ions. Selectivity concentration for Hg(II) relative to a number of potential interfering ions was investigated. The sensor is highly selective for Hg(II) ions over a large numbers of cations with different charges. The sensor has been found to be chemically inert showing a fast response time of 60 s and was used over a period of 3 months with good reproducibility(S = 0.27 mV). The electrode was successfully applied to determine mercury in real samples with satisfactory results. In second part of this work, a new ion selective PVC membrane sensor is described as a potentiometric sensor for the determination of Hg 2+ ions. The membrane having bis(benzoyl acetone) diethylene triamine as an electro active material, sodium tetraphenyl phthalate(NaTPB), and dibutyl phthalate(DBP) as an anion excluder in PVC matrix in the percentage ratio of 4.21:2.11:60.25:33.43(Ionophore:NaTPB:DBP:PVC) (w/w). The sensor exhibits a linear response to Hg(II) ions in a concentration range of 1.0 × 10 -6 to 1.0 × 10 ?1 M, with a limit of detection of 3.7 × 10 ?7 M Hg(II) and with a slope of -29.8±1.0 mV/decade over the pH range 2.0-11.5. Selectivity coefficients for Hg(II) relative to a numbers of potential interfering ions were investigated. The sensor is highly selective for Hg 2+ ions over a large number of mono-, bi-, and trivalent cations. Normal interferents like Ag + and Cd 2+ did not interfere in the working of the sensor. The sensor showing a fast response time of 1 s and was used over a period of 3 months with a good reproducibility. The sensor was successfully applied to determine mercury(II) in water samples with satisfactory results. In third part of this work, an amiloride ion selective PVC membrane electrode based on an ion-pair complex with sodium tetraphenyl borate was prepared with DBP as a plasticizer. The electrode exhibits a linear response with an approximate Nernstian slope(-54.3 mv/decade) within the concentration range 1.0 × 10 -5 to 1.0 × 10 -2 M amiloride and with detection limit of 9.9 × 10 -6 M. The working pH range is 2.0-7.0. This electrode is very stable and has a good reproducibility and fast response time(~6 s).The selectivity of the electrode toward cations, lactose and some pharmaceutical compound was found to be satisfactory. The sensor was successfully applied to determine amiloride in drug samples with satisfactory results.