A new one-step method of preparation of solution processable conductive polyaniline (PANI) is reported using didecyl ester of 4-sulfophthalic acid (DESPA) as multifunctional material. It consists of inversed emulsion polymerization of aniline in water/chloroform mixture with benzoyl peroxide initiator, maleic acid (MA) as a codopant and DESPA as protonating agent, surfactant, and plasticizer. The resulting product combines reasonable conductivity (ca.0.03 S/cm) with solubility in common solvents such as tetrahydrofuran and chloroform. Elemental analysis together with spectroscopic studies show that the protonation level of emulsion polymerized PANI (0.47 per mer involving one ring and one nitrogen) is very close to that predicted for PANI in the oxidation state of emeraldine (0.5). MA is incorporated into the polymer matrix as a co-dopant in the ratio 1:4 with respect to the DESPA dopant. PANI-DESPA-MA three components system shows a highly ordered, layer-type supramolecular structure, in which planes of regularly pi-stacked PANI chains are separated by a double layer of dopants. (c) 2007 Wiley Periodicals, Inc.