In this thesis, a simple method has been used to fabricate selective membrane chemical sensors for the estimation of polyionic compounds. These compounds are composed of repeating units embracing electrolytic functional groups, therefore, they contain a large number of positive or negative charges. Such compounds are of great importance in biology and biochemistry as many of the biological molecules are considered as polyionic species. In these aspects, such compounds are utilized in water purification and in precipitating soluble viruses. They are also used in many industrial processes such as the food industry and detergent industries and also in the petroleum industry, as well as pharmaceutical industry. Therefore, the development of simple, fast, and low-cost methods for the quantitative determination of the low-levels of such compounds in different types of samples was an important demand. So, This research introduces a simple method for the quantitative determination of the concentrations of some polyanionic species, namely dextran sulfate and sodium polytungstate, as well as the polycationic species protamine sulfate, in a number of industrial and pharmaceutical products. The developed method depends on the fabrication and use of a potentiometric polymeric membrane electrode in the determination of polyionic compound concentrations. The fabricated sensors are characterized by their sensitivity..