Conductive polymers are organic compounds characterized by conjugated double bonds, and therefore have the properties of electrical conductivity in addition to those of conventional polymers such as low weight, corrosion resistance and cheap fabrication. In addition to conjugated bonds, to achieve conductivity, it is necessary to have free charge carriers, which is achieved by oxidation or reduction of the polymer. Conductive polymers have been used in corrosion protection, electrostatic protection of devices, electrochromic devices, and more recently in the field of chemical sensors and biosensors. One of the most commonly used conductive polymers is poly(3,4-ethylenedioxythiophene) (PEDOT), which is obtained by electrochemical or chemical oxidation polymerization. In this work PEDOT conductive polymer was synthesized by chemical oxidation polymerization, with the ammonium persulfate ((NH4)2S2O8) oxidant. PEDOT conductive polymer was prepared with four defined ratios of EDOT monomer and oxidant, 1:1, 1:2, 1:4 and 1:6. In order to confirm the successfull the synthesis of PEDOT polymer samples, characterization was performed by infrared spectroscopy with Fourier transformations (FTIR). The four-point probe method was used to determine electrical conductivity of the samples and cyclic voltammetry was recorded for all PEDOT samples. Thermogravimetric analysis (TGA) was used to determine thermal stability of the tested samples. The results showed that by increasing the ratio of monomers to oxidants, the degree of polymerization decreases and the conductivity reduces. It has been found that monomer: oxidant ratios above 1:2 adversely affect the structure of PEDOT. Furthermore, a sample with a ratio of 1:6 degrades the polymer due to the overoxidation of PEDOT with a strong oxidant.