The differential pulse voltammetric method was developed for simultaneous determination of dopamine (DA) and acetaminophen (AC) using the Ppyox/AZ/Au (poly overoxidized pyrrole-aszophloxine-gold) modified electrode. Polypyrrole film was prepared by incorporation of aszophloxine (AZ) as doping anion, during the electropolymerization of pyrrole onto a gold (Au) electrode in aqueous solution using the cyclic voltammetric (CV) technique. Then the polypyrrole film was overoxidized at constant potential. Well-separated voltammetric peaks were observed for dopamine (DA) and acetaminophen (AC) with peaks separation of about 200 mV. The current of the oxidation peaks showed a linear dependent on the concentrations of DA and AC in the range of 0.1-30 mu M and 0.2-100 mu M respectively. The detection limit of 0.05 and 0.08 mu M (S/N = 3) were obtained for DA and AC respectively. The modified electrode was used for determination of DA and AC in some real samples such as human serum and tablet samples. (C) 2012 Elsevier B.V. All rights reserved.