The present small-angle X-ray scattering (SAXS) investigations reveal solvent-assisted conformational modifications in the conducting polymer polyethylene dioxythiophene (PEDOT) doped with polystyrene sulfonate (PSS). The dimensionality of PEDOT-PSS chains in water, glycerol and dimethyl sulfoxide (DMSO) solutions, obtained from SAXS profiles, are 2.68-2.3. Radius of gyration values from pair distribution functions analysis are used to identify the Guinier regime, and give evidence for chain expansion in glycerol and DMSO solutions, with improved assembly of chains. Conformational modifications are suggested to enhance the conductivity of PEDOT-PSS films in glycerol/DMSO solutions. (c) 2006 Elsevier B.V. All rights reserved.