The risk of mercury poisoning especially from environmental water is prevalent. Hence, there is a pressing need to monitor the level of mercury therein by for example the simplest technique utilized i.e. ISE. However, most of these are limited to a certain pH range, in particular acid region, incorporation of elaborate or exotic ionophores and of heterogeneous membrane types. Until now there is no report as yet on the usage of poly (4-vinylpyridine) (P4VP) and poly-2,6- diaminopyridine (PDAP) as ionophores in Hg-ISEs. This study aims at preparing ion selective electrode for the determination of mercury (II) ions using these two conducting polymers. Two types of ISE are investigated (a) heterogeneous solid membrane using P4VP and (b) Coated wire electrode using PDAP. The fabricated sensors will be optimized prior to analysis of Hg in real samples taken from (sea water, industrial wastewater, etc.)