Tungsten oxide was electrochemically deposited from a metastable acidic solution of isopolytungstate on glassy carbon electrodes coated by the films of a conducting polymer poly-3,4-ethylenedioxythiophene (PEDOT). The formation of PEDOT/WO ₃ composite films during electrochemical deposition of tungsten oxide into the polymer matrix was gravimetrically monitored by EQCM. The morphology of WO ₃ deposits was studied using SEM, TEM and EDX analysis, including element mapping and depth concentration profile of main elements. SEM and TEM images of PEDOT/WO ₃ composites show disperse distribution of WO ₃ precipitates in the porous matrix of PEDOT, possessing high surface area and pore volume, effective for charge transport. Electrochemical behavior of PEDOT/WO ₃ was investigated in 0.5 M H ₂ SO ₄ by cyclic voltammetry, galvanostatic charge-discharge method and electrochemical impedance spectroscopy. The WO ₃ component in the obtained PEDOT/WO ₃ composite electrodes exhibited high specific capacitance of 689 F g ⁻¹ in the potential range −0.3–0.0 V. The work presents a simple approach for the synthesis of PEDOT/WO ₃ composites with high values of specific capacitance. The obtained results indicate that PEDOT/WO ₃ composite could be a promising electrode material for supercapacitor applications.