Abstarct: Recently, modification of electrodes with a thin laxyer of polymeric films by means of simple and fast electro-polymerization method has received considerable attraction by the electro-analytical researchers. The polymeric films obtained have distinct advantages such as good physical stability, reproducibility, homogeneity, strong adherence to the electrode surface, and electro-catalytic activity. Therefore, several papers have been published on the modification of electrodes with different polymers and their electrochemical applications. In this thesis, we describe the electroanalytical performance of poly(solochrom black T), poly(eriochrom black T) and poly(hydroxynaphtol blue) as excellent modifiers in the construction of a voltammetric sensor. In the first section, glassy carbon electrode was modified with a thin film of poly (solochrom black T) and applied for the sensitive and selective voltammetric simultaneous determination of dopamine and acetaminophen. The preparation and basic electrochemical behavior of poly (solochrom black T) film on the glassy carbon electrode were investigated in details. The cyclic and differential pulse voltammetric studies showed that the modified electrode with polymeric thin film exhibits excellent electrocatalytic activity towards the oxidation of dopamine (DA) and acetaminophen (AP). The modified electrode was used as a voltammetric sensor for sensitive simultaneous determination of dopamine and acetaminophen free from ascorbic acid and uric acid interferences. Under the optimum conditions, the detection limits were 0.092 and 0.142 µmol L−1 for DA and AP, respectively. The proposed sensor has been successfully used in analysis of pharmaceutical and biological samples. In the second section, a sensitive and selective voltammetric sensor was developed for the simultaneous determination of catechol (CC), resorcinol (RS), and hydroquinone (HQ). The sensor was simply constructed by electro-deposition of a thin film of poly(eriochrome black T) on the surface of glassy carbon electrode (poly(EBT)/GCE). The electrochemical oxidation of catechol, resorcinol, and hydroquinone using poly(EBT)/GCE was also investigated by differential pulse voltammetric techniques (DPV). The detection limits for HQ, CC and RS were 0.20, 0.11 and 0.60 µmol L−1 (3σ), respectively. The modified electrode was applied to simultaneous determination of three dihydroxybenzene isomers in the water samples with satisfactory results. In the third section, we describe the fabrication of poly(hydroxynaphthol blue)/multi-walled carbon nanotubes (poly(HNB)/MWCNTs) film modified glassy carbon electrode and its application for the simultaneous determination of diclofenac (DCF) and acetaminophen (AC) was reported using differential pulse voltammetry. We reported for the first time on a polymer film of HNB to modify glassy carbon electrode and described the electrochemical behavior of the novel poly(HNB)/MWCNTs modified glassy carbon electrode. The oxidation of DCF and AC species were also studied at the surface of modified electrode by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The proposed electrochemical sensor exhibited an excellent electrocatalytic activity towards the oxidation of the two analytes and thus was used for the simultaneous voltammetric measurement of DCF and AC by DPV. Under the optimum experimental conditions, the detection limits for DCF and AC were 0.31 and 0.19 µmol L−1, respectively. The proposed method was also successfully applied to the simultaneous determination of DCF and AC in pharmaceutical and biological samples. In the fourth section, a voltammetric sensor is developed baxsed on a poly(hydroxynaphthol blue)/multi-walled carbon nanotubes modified glassy carbon electrode for the simultaneous determination of the dihydroxybenzene isomers. The preparation and basic electrochemical performance of the sensor are investigated in details. The electrochemical behavior of the dihydroxybenzene isomers at the sensor is studied by the cyclic and differential pulse voltammetric techniques. The results obtained show that this new electrochemical sensor exhibits an excellent electrocatalytic activity towards oxidation of the three isomers. Under the optimum experimental conditions, the detection limits were 0.24, 0.24, and 0.26 µmol L−1 for hydroquinone, catechol, and resorcinol, respectively. The proposed sensor is also used in the analysis of different water samples.