Structure and electrophysical properties of poly(3,4-ethylenedioxythiophene) (PEDOT) films electrochemically doped with PF6-, BF4-, and CF3SO3- have been studied. According to SEM and XRD studies, doped PEDOT films have amorphous fibrillar structure. Thermal studies show that continuous degradation occurs above 150 degrees C and complete decomposition above 390 degrees C. Temperature dependence of the de conductivity of best doped PEDOT samples was very weak and characteristic resistivity ratio rho(r) = rho(1.4 K)/rho(291 K) was less than 2. For these most conducting PEDOT samples the temperature coefficient of resistivity (TCR = Delta rho/rho Delta T) changes sign below 10 K from negative to positive which is characteristic for normal metals. SQUID data are in good agreement with the conductivity results.