The DC conductivity ( σ DC) of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(4-styrenesulfonate) (PSS) with various organic solvents was measured. The solvents used were dimethyl sulfoxide (DMSO), N, N-dimethyl formamide (DMF), tetrahydrofuran (THF), and H 2O (as pristine solvent). Room temperature DC conductivity σ DC(RT) of a free standing film of PEDOT/PSS with H 2O was measured to be ∼0.8 S/cm. Through a change of solvents used, σ DC(RT) of the samples increases from ∼0.8 to ∼80 S/cm. The temperature dependence of DC conductivity σ DC( T) of PEDOT/PSS with H 2O followed a quasi one-dimensional variable range hopping model, while that of PEDOT/PSS prepared from DMSO, DMF, and THF followed a power law ( σ DC ∝ T β ). From X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) experiments, the doping concentration of the systems with different solvents was approximately the same. We analyzed that the screening effect of the solvent plays an important role for the variation of σ DC of the PEDOT/PSS systems.