Polyaniline has been synthesized by a chemical route. Chemical doping of polyaniline has been carried out with copper perchlorate tetrabenzonitrile (CuClO4 center dot 4BN) in a distilled water (H2O) + dimethylsulfoxide (DMSO) solvent system. An effort has been made to study the effect of dopant on polyaniline by electrical and dielectric measurements and Fourier transform infrared spectroscopy. Electrical conductivity and dielectric parameters such as dielectric constant, dissipation factor, and dielectric loss have been measured at different dopant concentrations and temperatures. An increase in electrical conductivity, dielectric constant, dissipation factor, and dielectric loss with an increase in the dopant concentration as well as temperature has been observed in all the samples. It has been observed that CuClO4 center dot 4BN dopant in polyaniline plays an important role in enhancing the conductivity of polyaniline. In addition, aqueous dimethylsulfoxide is found to be a suitable solvent for polyaniline doping with CuClO4 center dot 4BN. (C) 2011 Wiley Periodicals, Inc. Adv Polym Techn 31: 374379, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20260