Conductive polymers are type of synthetic polymers that have alternating single and double bonds in the structure that give them the ability to conduct charge. They combine the positive properties of metals and conventional polymers - the ability to conduct charge, excellent electrical and optical properties - with flexibility in processing and ease of synthesis. In addition to conjugated bonds to achieve conductivity, it is necessary for them to have free charge carriers, which is achieved by the addition of dopant, cations or anions that can move along the polymer chain. Conductive polymers have found application in advanced technologies such as electrochemical energy sources, photovoltaic devices and biosensors. One of the most commonly used conductive polymers is poly(3,4-ethylenedioxythiophene) (PEDOT), which can be obtained by electrochemical or chemical polymerization. In this work, the synthesis of PEDOT was performed by chemical oxidation polymerization with iron(III) chloride (FeCl3) oxidant with a well-defined ratio of 3,4-ethylenedioxythiophene (EDOT) monomers and oxidants (1:1, 1:2, 1:4, 1:6). The samples were characterized by Fourier transform infrared spectroscopy (FTIR), electrical conductivity measurement, cyclic voltammetry and thermogravimetric analysis (TGA), which determined the composition and the properties of the synthesized polymers. The results showed that increasing the ratio of monomers and oxidants improves the electrochemical properties of PEDOT up to a ratio of 1:4, after which the polymer chain over oxidation occurs and the properties decrease.